QCA wireless settings

From DD-WRT Wiki

Jump to: navigation, search


[edit] Introduction

This page shows the contents and descriptions of standard and advanced wireless settings for Qualcomm Atheros (QCA) based 802.11a/b/g/n/ac/ad routers. Not every router shows every possible setting shown here as some routers will have less. If you are a Broadcom or Mediatek (formerly Ralink) user, please refer to this page for Broadcom/Mediatek wireless settings.

[edit] Standard Settings

[edit] Wireless Physical Interface

Available Interfaces: athX (0, 1, 2 etc, varies by router as many routers have 2 or more radios in them)

If you have a dual band router ath1 will be displayed below ath0 with the same available settings. Ath0 is the 2.4GHz radio and ath1 is the 5GHz radio for most routers, for some like the TL-WDR4900 v1.3, ath0 is 5GHz & ath1 is 2.4GHz; its just the way the radios are connected on the PCB & is normal. If you create a VAP for 2.4GHz or 5GHz radio the VAPs will be labelled athX.1 & athX.1 respectively where X = the interface's number. For example, a VAP made on ath0 will be ath0.1, then ath0.2, etc. Refer to this thread for some info about VAPs with Qualcomm Atheros.

[edit] Wireless Mode

Available Settings: AP, Client, Client Bridge (Routed), AdHoc, WDS Station, WDS AP

Default Setting: AP

Recommended Setting: AP for most users, other options if you are advanced and know you need it

Determines how the specific wireless interface of the router is to behave. If you want to run a normal access point which most do, AP would be your choice. Client, Client Bridge (Routed), & WDS Station is the Qualcomm Atheros equivalent to Broadcom & Mediatek's Repeater and Repeater Bridge modes.

[edit] Wireless Network Mode

Available Settings (2.4 GHz): Disabled, Mixed, B-Only, G-Only, BG-Mixed, NG-Mixed, N-Only (2.4 GHz)

Available Settings (5 GHz): Disabled, Mixed, A-Only, NA-Mixed, AC/N-Mixed, N-Only (5 GHz), AC-Only

Available Settings (60 GHz): Disabled, Mixed, AD-Only

Default Setting: Mixed

Recommended Setting: Mixed or NG-Mixed (2.4 GHz), Mixed or AC/N-Mixed (5 GHz), AD-Only (60 GHz)

Controls which 802.11 signals are being broadcast by the radio. Depending on the selected network mode your wireless channel list and maximum TX power can vary. NG-Mixed for 2.4 GHz & Mixed or AC/N-Mixed is the recommended setting for most people as your clients' NICs are able to use either (V)HT20, (V)HT40, & VHT80 "properly" with this setting. If you have any issues or do not use 802.11b clients, switch to NG-Mixed. N-Only is broken on many units for some time (both bands) & still is, try to avoid using as there is minimal performance change from NG-Mixed -> N-Only if all you use is 802.11n clients for either of them. For 802.11a/n 5 GHz radios, Mixed & NA-Mixed are the same.

[edit] Channel Width

Available Settings: Dynamic (20/40 MHz), VHT160*, VHT160 (80+80 MHz)*, VHT80 (80 MHz)*, Wide HT40 (40 MHz), Full (20 MHz), Half (10 MHz), Quarter (5 MHz)

Default Setting: Full (20 MHz)

Recommended Setting: VHT160*, VHT80 (80 MHz)*, or Wide HT40 (40 MHz). Full (20 MHz) if using long range (3km+) links or have severe 2.4 GHz interference in your area.

This determines the width of the wireless channel where higher allows more bandwidth but less overlapping channels and lower allows more non-overlapping channels but less bandwidth. It is said that 40 MHz, which enables channel bonding by using two 20 MHz wide channels together, is not "neighbor friendly". This is correct as the wider channel creates more overlap onto other channels, which could (but usually doesn't) create more interference for neighbors, but usually is not an issue unless you are in a VERY packed wireless area. 40 MHz allows your 2.4 GHz 802.11n devices to connect at their max of 300 Mbps (or 450 Mbps for 3x3) when signal is sufficient, as well as a large throughput increase and enables Atheros Super-G*. If Full (20 MHz) is used for 802.11n clients the max connection speed will only be 144 Mbps (216 Mbps for 3x3) and 802.11g clients supporting Super-G max connection speed will only be 54 Mbps.

*Note: You MUST have this setting on Wide HT40 (40 MHz) to allow 802.11n devices (2.4 GHz & 5 GHz) to connect at their max!

*Note 2: 802.11g + Wide HT40 (40 MHz) = Super-G!*

*Note 3: VHT80 (80 MHz), VHT160 (80+80 MHz), & VHT160 is only displayed & available for 802.11ac (5 GHz) routers that support it, & is required to reach the high link rates of 802.11ac

[edit] *Super-G

This is a Qualcomm Atheros technology to increase the throughput of 802.11g devices and NOT compatible with 40 MHz channel width in 802.11n. In order to utilize the Super-G feature you must have a QCA router capable of broadcasting 40 MHz wide channels which nearly all QCA routers support this feature, and a Super-G ready client. If you have a QCA router and Super-G ready client, ensure your wireless network mode is on Mixed, G-Only or "NG-Mixed" with Wide HT40 (40 MHz) as the channel width. The client should now connect at the theoretical max link rate of 108 Mbps, doubled that of standard 802.11g 54 Mbps. This feature reaches these speeds by channel bonding, a method that bonds two 20 MHz wide channels together similar to how 802.11n does. Max throughput with Super-G should be around 75 ~ 80 Mbps depending on distance, SNR, noise, & other wireless settings. Super-G has no presence or specific controls on the user interface, its automatically on or off & is a zero config feature.

[edit] Wireless Channel

Available Settings (2.4 GHz): Channels 1 ~ 14 depending on your regulatory domain & channel width

Available Settings (5 GHz): Channels 34 ~ 48 (U-NII-1), 52 ~ 64 (U-NII-2), 100 ~ 144 (U-NII-2e), 149 ~ 161 (U-NII-3), 165 (ISM) depending on your regulatory domain*

Available Settings (60 GHz): Channels 1 ~ 4 depending on your regulatory domain*

Default Setting: Auto

Recommended Setting: Use the cleanest channel with the least noise, most stable throughput, & lowest latency jitter

Controls what channel or frequency your wireless LAN (WLAN) uses. If you have packet loss, abnormally slow throughput or drop outs switch to another channel for less interference. Use site survey & experiment with using different channels, its best to use a channel thats 4 or 5 channels away from the other in use channel for zero interference from other WLANs but since thats hard in this small spectrum even just 2 or 1 channel away makes a massive difference despite there still being a partial overlap, see the images & this link for more info. All routers default to either channels 1, 6, or 11 (for 2.4 GHz) when left on the "auto" setting, it is not recommended to use these channels as most users are inexperienced, and leave them at their defaults. Most of these channels are noisy but for any reason if there isn't many APs around you using these channels, use them.

  • Available channels will vary greatly by region & there is no place on Earth where every channel is available legally. Only channels 149-165 allow high TX power up to 30 dBm in most of the world, only a few countries allow 30 dBm from channel 100+, using a foreign regulatory setting to bypass your local laws is not recommended & is at your own risk. As of 2014 the FCC has announced that the lower 5 GHz band (U-NII-1) will have it's "indoor only" requirement lifted, & max power output/EIRP increased to 24 dBm.

[edit] Extension Channel

Available Settings (40 MHz): Upper, lower

Available Settings (80 MHz): UU, LL, UL, LU

Available Settings (160 MHz): UUU, LLL, ULU, LUL, UUL, LLU

Available Settings (60 GHz): TODO

Default Setting: Auto

Recommended Setting: Any*

This setting is only valid when Wide HT40 (40 MHz), VHT80 (80 MHz), VHT160 (80+80 MHz) or VHT160 (160 MHz) is used for channel width. It controls the extension channel(s), which is the other channel(s) used to attain the 40 MHz width or in the case of 802.11ac, 80/160 MHz width the other 3 channels, are above &/or below the primary selected channel. Build r29974 & later have fixed the extension channel lower setting, use upper or lower depending which channel you want. Builds older than r29974 have problems with ext channel setting & channel selection list. Builds after r31277 have added full range of upper/lower & in between, options for channel widths above 40 MHz for 802.11ac.

Valid VHT80 channels are:

  • 36+UU
  • 40+UL
  • 44+LU
  • 48+LL
  • 52+UU
  • 56+UL
  • 60+LU
  • 64+LL
  • 100+UU
  • 104+UL
  • 108+LU
  • 112+LL
  • 116+UU
  • 120+UL
  • 124+LU
  • 128+LL
  • 132+UU
  • 136+UL
  • 140+LU
  • 144+LL
  • 149+UU
  • 153+UL
  • 157+LU
  • 161+LL

Valid VHT160 channels are:

  • 36+UUU
  • 64+LLL
  • 100+UUU
  • 128+LLL

  • Of coarse this depends on the regulatory domain & client devices in use.

[edit] TurboQAM (QAM256) support

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disable

Only valid for 2.4 GHz & for routers with QCA99xx & newer radios, this setting enables support for QAM256, which is what 802.11ac uses for its more efficient, higher link rates, even at the same channel width. Cause this is in 2.4 GHz, only up to 40 MHz widths can be used, if signal is strong enough, higher QAM allows more efficient use of the same amount of spectrum space, on devices that support this feature. With current builds this feature is broken, once enabled no devices connect to the 2.4 GHz band, even if they support QAM256 on 2.4 GHz, therefor its recommended to disable this for now.

[edit] Wireless Network Name (SSID)

Default Setting: ddwrt

This is where you can choose the name of your wireless network when its being broadcast to roaming clients. You can name this anything you want.

[edit] Wireless SSID Broadcast

Available Settings: Enable, disable

Default Setting: Enable

Recommended Setting: Enable

Dependent on the setting above, this controls if your SSID is being broadcast or not. When disable is selected many clients still pick up the beacon and display it as "Hidden" along with the AP's MAC address. Disabling is not recommended as it hardly does anything for security, a determined intruder can still access your network with different methods.

[edit] Advanced Settings

  • Builds >=r14815 have a tab to show or hide advanced wireless settings.

[edit] Regulatory Domain

Available Settings: 115+ different countries (several countries share the same regulations)

Default Setting: Germany

This determines the channels available in the list for both bands (if you have a dual band router) and the maximum EIRP "legally" allowed by the telecom authorities in the chosen country. EIRP is TX power plus antenna gain, example:

  • 20 dBm TX power with a 10 dBi gain antenna has an EIRP of 30 dBm.
  • 24 dBm TX power with a 6 dBi gain antenna has an EIRP of 30 dBm.

Maximum EIRP varies by nation and your max TX power will be capped by the regulatory domain if you have a powerful radio. For example, Canada's max allowed EIRP is 36 dBm while its max allowed TX power is 30 dBm, with Canada selected and antenna gain at 0 dBi, the radios will never go above 30 dBm assuming they are capable of reaching that of coarse.

[edit] TX Power

Available Settings: 0 ~ 999

Default Setting: 16 ~ 30 dBm (varies by router)

Recommended Setting: Highest dBm your radios & local laws legally allow**

Transmit (TX) power is the amount of "current" or "juice" going to the antennas, it is NOT the output power FROM the antennas, as that is EIRP. Usually more TX power is better as it allows clients further away to "hear" your AP (assuming the clients also have near equal TX power so the AP can "hear" them back). If TX power is increased too much on older radios, excess noise can develop and reduce throughput or even range; this is an issue with most Broadcom routers. But with Qualcomm Atheros this does not seem to be much of a problem as most QCA radios work very well at their max TX power. Maximum TX power is controlled by the radios (power control*), regulatory domain, wireless channel used, & wireless channel width. The default value for most routers currently is 20 dBm. If you want to run the highest TX power possible, enter 30 dBm & the radios will use as high as their lowest limiter allows (being regulatory domain, channel, or radio EEPROM cap), most can't do 30 dBm so what's displayed on the wireless status page is what's being used. Some newer routers can get very close to or even at 30 dBm, which is the current highest allowed TX power for any regulatory domain.

*Power control

An automatic zero config feature which controls the max TX power by the SNR & link speed. The higher the SNR, the lower the TX power will be (this action does not display on the wireless status GUI). See vendor specs/FCC documents for more info.

**Recommended Setting

Some people believe that "high" TX power (i.e., greater than 25 dBm), may be of concern to one's health. That is not the case but each to their own. So if that's you then 22 - 25 dBm should be sufficient; any lower & range starts to significantly drop (unless you want to of course & if you have an older router than only does something like 18 dBm, no need). In case you are wondering, every 3 dBm is doubled the power, so 13 dBm is twice as much as 10 dBm, & so on; but don't worry, 30 dBm is only 1 watt.

[edit] Antenna Gain

Default Setting: 0 dBi

Recommended Setting: 0 dBi

Antenna gain is amount of "gain" or "boost" of signal that the antenna provides. Its a bit complicated but remember this, antennas are not amplifiers. They do not magnify the signal, but instead "focus" the signal in certain directions, yes even omni-directional antennas do it. The higher the gain the better as it increases EIRP which somewhat helps extend range and significantly helps sensitivity. With high sensitivity, the AP is able to hear "faint" clients, clients that may have a low TX power or are just simply very far away. Set this to 0 as its useless, it does not function anymore & always assumes a value of 0 within the wireless drivers.

Normally it would function as so: take gain into consideration when calculating EIRP, depending on regulatory setting an example of 25 dBm EIRP (20 dBm TX power + 5 dBi gain) may be too high when the limit is lets say 22 dBm EIRP, the TX power in this case will be forced down to 17 dBm. Antenna gain setting has no effect on performance of the WLAN directly (but a physical quality high gain aftermarket antenna does!).

[edit] Noise Immunity

Available Settings: Enable, Disable

Default Setting: Enable

Recommended Setting: Enable

Controls radio sensitivity in noisy environments by tuning driver parameters from info based on but not limited to, OFDM/CCK errors, beacon RSSI levels, OFDM weak detection, FIRPWR, FIRSTEP_LEVEL, CYCPWR_THR1. The goal of noise immunity is in the name, to help make the router more "immune" to noise, its generally recommended to leave this enabled, only disable if you are an advanced user, are diagnosing various wireless issues, or it fixes a specific issue you were having. Especially if you have multiple Qualcomm Atheros routers connected to eachother in any way, its highly recommended to have noise immunity enabled or disabled on all routers, not mixed. There has been some reports over the years that disabling noise immunity has helped stabilize the WLAN in terms of throughput &/or reducing dropouts, disabling noise immunity could also result in great or unchanged close range performance, but horrible or no throughput whatsoever, at medium ~ far range, so experiment with this setting. There is also some cases where enabling noise immunity gives abnormally low TX/RX rates & throughput, or noise immunity is simply too aggressive even in low noise, in this case, disable, but start with enabled first.

[edit] Protection Mode

Available Settings: None, CTS, RTS/CTS

Default Setting: None

Recommended Setting: RTS/CTS or None for AP modes, & RTS/CTS for client modes

This setting controls whether the request to send/clear to send 802.11 optional protection mechanism is enabled or disabled. When enabled, an RTS/CTS handshake must be completed before data can be transmitted from clients. Helpful in noisy &/or busy environments, it ensures all clients take turns communicating with the AP, if disabled, packet collisions may occur which causes a drop in throughput & increase in latency due to retransmission overhead. RTS/CTS also helps negate the hidden node problem which occurs when 2 or more clients can each see the AP & vice versa, but the clients can't see eachother, this example is also good to say why RTS/CTS on an AP has no use, since from the AP's point of view, it can already see all connected clients, or they wouldn't be connected in the first place. CTS only is "CTS-to-self" which has less overhead, but is less effective in mitigating the hidden node issue, only other clients within range of the client using CTS only, will hear & honor it while RTS/CTS is the "full option" that gets passed through the AP to all clients, even if the AP has RTS/CTS disabled since RTS/CTS on the AP only applies to when the AP wants to transmit.

RTS/CTS is a setting to experiment with especially on the client mode interface of the router if you are connecting a router to another router, or if you have high error rate or high noise floor (-90 noise is good, -60 is bad) & all other options have failed. Most users should leave this set to the recommended setting above for max performance because the protection mechanism is only enabled automatically when needed, if its off when its needed, your wireless performance can plummet with errors, disconnects & low throughput, & if its no longer needed its turned off automatically on the fly.

If all that wasn't enough, protection modes also matter depending if you are using any kind of mixed modes such as mixed or NG-mixed, & if the older clients are connected or not. As well if you are using HT40 or VHT80 when there will be clients connected that don't support above HT20. In such case, you MAY want to have some protection mode, but usually with today's routers you are able to mix client types without penalty. If performance is good still without protection, continue to use none.

[edit] RTS Threshold

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Enable (2346) or Disable for AP modes, Enable (2346, or slightly lower if NEEDED) for client modes

Only valid if RTS/CTS or CTS is enabled, this sets the maximum packet size before the RTS/CTS protection is enabled, if you still have high packet collisions with RTS/CTS enabled and RTS Threshold at it's default, try lowering it by 10-50 at a time. Lowering it too much can further create overhead and reduce performance as RTS/CTS frames themselves also take up air time & aren't immune to collisions, a good minimum limit is 500 ~ 600, any lower & you'll probably spend more air time transmitting & exchanging these frames than the actual data frame themselves, nullifying any benefit it could of provided as a large amount of the client's communication frames to the AP are <500 ~ 600 bytes at a time. Leaving this on the default setting 2346 theoretically disables the RTS feature and only leaves CTS enabled as most packets don't exceed 2346 bytes.

[edit] Short Preamble

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Enable

If you have 802.11b clients in your network you can try enabling this, but if they have problems with performance or connecting, then leave it disabled. Preamble is at the head or front of the PLCP, which devices need in order to start transferring data. The long preamble ensures compatibility with legacy 802.11b devices but will slightly reduce throughput at higher data rates along with possibly introducing WLAN instability &/or overhead. Short preamble support, which is reducing the header's size by 50% down to 9 bytes, is optional for 802.11b. 802.11g & newer all support short preamble as its part of specification, so if you do not have 802.11b devices in your network, or any that you may have work fine with short preamble, leave this enabled at all times.

[edit] Short GI

Available Settings: Enable, Disable

Default Setting: Enable

Recommended Setting: Enable

The standard guard interval used in 802.11 OFDM is 0.8 μs, to increase data rate 802.11n added optional support for a shorter 0.4 μs guard interval which provides about a 10% increase in data rate. The shorter guard interval could (but usually doesn't) result in a higher packet error rate if timing synchronization between the transmitter and receiver is not precise. To reduce complexity, short guard interval is only implemented as a final rate adaptation step when the device is running at its highest data rate such as 72 Mbps, 144 Mbps, 300 Mbps etc, this is by design & not changeable.

Older routers & devices with Atheros AR92XX radios or older only support short GI on HT40 & not HT20, so max HT20 rates are 65 Mbps/130 Mbps/195 Mbps (1x1/2x2/3x3) instead of 72 Mbps/144 Mbps/217 Mbps respectively. Some modern devices such as the Playstation 4 do not like the lack of short GI, & have strange performance problems, sometimes completely crippling the entire network's performance. But the issue may also be related to hardware bugs in the AR92XX chipset, mileage may vary.

[edit] Single User Beamforming

Available Settings: Enable, Disable

Default Setting: Enable

Recommended Setting: Enable

Controls whether 802.11ac beamforming is enabled for single user, aka "regular MIMO" connected devices that support beamforming. For 2.4 GHz, beamforming is only supported & broadcasted in beacon info when TurboQAM is enabled.

[edit] Multi User Beamforming

Available Settings: Enable, Disable

Default Setting: Enable

Recommended Setting: Enable

Controls whether 802.11ac beamforming is enabled for multi user, "MU-MIMO" connected devices that support beamforming. Since MU-MIMO is a 802.11ac wave 2 feature, all wave 2 devices will support beamforming & MU-MIMO. For 2.4 GHz, beamforming is only supported & broadcasted in beacon info when TurboQAM is enabled.

[edit] TX & RX Antenna Chains

Available Settings: 1, 1+2, 1+3, 1+2+3, 1+2+3+4 (varies by router)

Default Setting: Varies by router

Recommended Setting: Varies by router

This setting is critical for proper, smooth, fast Wi-Fi performance. 2x2:2 routers will either have TX/RX chains at 1+2/1+2, 1+3/1+3, 1+2/1+3, or 1+3/1+2. This can take some time to find the proper setting but its worth it, you can more easily find the correct setting by using a 802.11n client thats capable of 300 Mbps link. Note the TX/RX link rates on the wireless status page, when set incorrectly one or both of the rates will drop to a much lower speed such as 200, 170, 81 etc. This is best done with the client less than 10 feet from the AP with clear line of sight. Some routers with chains set incorrectly such as D-Link DIR-615 C1, will deny connections to clients, heavily reduce throughput, and other errors. Searching the FCC ID of your router will aid in setting the correct chain settings. Some popular routers such as the Netgear WNDR3700 v1/2/4 and D-Link DIR-825 B1/B2 require both chains set at 1+2 for proper Wi-Fi performance. Default is not always right!*

*With builds around r21061 or later, most units have the proper defaults preset & invalid options removed, such as 1+2+3 for TX/RX on WNDR3700 v1, v2, & v4 as the router only has 2 chains each therefor only has 1 & 1+2 available to be selected. While a TL-WDR4900 v1.3 & v2 have 1+2+3 as they are 3x3:3 units. An example 4x4:4 unit is the R7800.

[edit] AP Isolation

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disable for private home Wi-Fi with trusted users, enable for public/guest Wi-Fi hotspot

AP Isolation allows clients connected to the same AP to communicate with each other or not, very much like Ad-Hoc mode. If you run a public Wi-Fi hotspot its recommended you enable this for privacy/security reasons & to help mitigate Wi-Fi snooping attacks that reveal login info such as this. If you want files to be shared from client to client in your home network, AP isolation must be disabled. This setting does not influence Wi-Fi throughput. If this setting is enabled it will break AdHoc based play on gaming devices such as Nintendo's DS system.

[edit] Beacon Interval

Available Settings: 15 ~ 65535

Default Setting: 100

Recommended Setting: 50 ~ 300 for 2.4 GHz & 75 ~ 250 for 5 GHz

A beacon frame, measured in milliseconds (ms), is one of the management frames in IEEE 802.11 WLANs. It contains all the information about the network & has a close relationship to the setting below it, DTIM interval. Beacon frames are transmitted periodically by the AP in an infrastructure BSS to announce the presence of a WLAN. Reducing beacon interval may help WLAN performance in noisy environments &/or with problematic clients such as some mobile tablets & phones but will decrease battery life. 100 is a typical default beacon setting but up to 250, even 300 can also work too more often than not. Increasing beacon interval would slightly reduce overhead & increase battery life, but possibly make the network more sensitive to noise & dropouts with buggy clients. "Overhead" when referring to beacon interval is airtime, beacons themselves also take up airtime which means less availability for data. For 5 GHz some routers default to 200 beacon interval such as the DIR-825 B1 stock firmware, DD-WRT default is 100 for both bands. Remember to adjust DTIM interval below, when changing beacon interval in order to keep the same DTIM period.

[edit] DTIM Interval

Available Settings: 1 ~ 255

Default Setting: 2

Recommended Setting: 2 ~ 5 (assuming default beacon interval of 100 is used)

Default being 2, the delivery traffic indication message (DTIM) is an element included in some beacon frames. It notifies the client stations that are currently in low-power mode that data buffered on the access point is awaiting pickup. The DTIM interval indicates how often clients serviced by the access point should check for buffered data, the buffered data is usually multicast/broadcast data. You specify DTIM in number of beacons. If you set this value to 2, clients check for buffered data on the AP on every beacon. If you set this value to 10, clients check the access point on every 10th beacon, this is assuming beacon interval is at the default of 100. 100 beacon & 1 DTIM = every beacon that occurs every 0.1 seconds will have a DTIM with it, beacon of 50 with 2 DTIM also = every beacon that occurs every 0.1 seconds will have a DTIM with it, & so on. More beacons/DTIMs in a shorter period can help multicast performance but hurt battery, less beacons/DTIM in a longer period may harm multicast performance, but help battery. The defaults are a good medium & are commonly used by stock firmwares on cheap & expensive routers world wide, this setting will require extensive testing if you wish to alter it.

[edit] WMM Support

Available Settings: Enable, Disable

Default Setting: Enable

Recommended Setting: Enable

Short for Wi-Fi Multimedia, is a Wi-Fi Alliance interoperability certification that provides a basic QoS "best effort" like function to Wi-Fi as well as other functions such as power saving, its a requirement & part of the 802.11n (& newer) specification. Disabling WMM will result in clients (ones that strictly obey specifications which is 90% of them) falling back to 802.11a/g rates (54M), the same way as using TKIP with WPA2 does.

[edit] Radar Detection

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disabled for most users. Enabled to comply with regulations where applicable.

Radar detection (AKA DFS: Dynamic Frequency Selection), if enabled, will change the frequency only when it identifies a military or doppler weather radar nearby on the same frequency. Most users shouldn't have any interference issues even those living near such locations. This applies to 5 GHz a/n/ac only.

[edit] ScanList

Default Setting: default

The frequency range in MHz, to be used by wireless radio (superchannel use requires this as they are non standard channels) & when searching for nearby APs, seperated by a dash (ie: "2600-2700" without quotes). Specially useful when using SuperChannel feature. Leave this at the default value (empty) unless you know what it does.

[edit] Sensitivity Range (ACK Timing)

Available Settings: 0 ~ 999999 (meters)

Default Setting: 2250

Recommended Setting: 0, or 900 - 2250* for both bands, greater than 2250 only when needed for long distance link. 0 (disabled) may also be tried especially if in a small or medium small home. If 0 is used, the router must be rebooted for it to disable ACK timing, on the wireless status page it'll show "N/A".

ACK timing is also a throughput controller, too high and your devices will literally be "waiting" too long and time will be passing with them at idle. Too low and active transmissions could be cut off causing retransmissions which create overhead, that lowers throughput. The AP sends a packet and all clients must wait for XXX time, where XXX is the ACK timing, the client then receives that packet and responds to the AP with an ACK(nowledgement), AP sees the AP then finally everyone is free to transmit.

Most users want this between 900 - 2250, the distance used is meters and needs to be doubled the distance of the furthest client from the AP (plus some headroom). Doubled because the signal travels to the client and back, double the distance. In earlier builds with the older MADWIFI driver reducing ACK from default 2000 to 1500 gave a throughput increase of 0.5 Mbps - 0.8 Mbps. Though with modern builds (r26653+) using the ath9k driver along with the internal changes to ACK timing, reducing to 1500 does little for throughput, one would have to drop at least 1250m. With the current ath9k builds an ACK timing of 0 does disable it** completely like on Broadcom & gives a slightly larger 1-3 Mbps increase over default. But if you do not disable ACK timing remember ACK timing too low can cause issues such as cutting off a still in progress transmission, causing a retransmission that half way to the destination, clashes with the returning ACK of the first transmission. This usually only happens with hidden nodes &/or clients that are distanced very far away/beyond ACK timing's set range but not always.

Long distance links, such as 4 KM+ will need to increase this setting accordingly. 4000m for 2km, 6000m for 3km, and so on, its good practice to add a little more ~10% or so, than the exact needed value to account for any overhead (CTS etc).

  • Current ath9k & ath10k drivers only use ACK timing in 450m intervals, being 0, 450, 900, 1350, 1800, 2250 & so on. Setting a value such as 300m will automatically use the closest valid entry, being 450 in this case & you will see so on the wireless status page, setting 1300 will actually use 1350 & so on.

  • 802.11g mode with a DWA-542 NIC got 21 Mbps with default 2250m on a TL-WDR4900 v1.3 with the latest build as of this posting (r27240), with ACK at 900m that rose to 22 Mbps, with ACK disabled it rose further to 23 Mbps & is mostly repeatable. Your results will vary depending on router, channel, clients & interference. Users in heavy interference areas may benefit from leaving ACK timing on vs turning it off, since there will be an increased number of clashed packets & retransmissions.

  • Builds r30342 & newer for ath10k devices have had several ACK timing changes, 450m is now a problematic setting causing extremely low TX rates, unusable latency & near 0 Mbps throughput. The new safety margin is now 900m minimum, or disabled (0 with 1 reboot after setting it there). The difference between 450m & 900m was very very tiny (back when 450m worked).

[edit] Max Associated Clients

Available Settings: 1 ~ 256

Default Setting: 128 ~ 256 (varies by router)

Recommended Setting: What suits you

Determines the maximum number of clients that can be connected to the AP at any given time. Hotspot users will find this very handy. Using a shorter DHCP lease time such as 2 ~ 12 hours instead of default 24 will also help free up IPs if you are finding 256 users is not enough for a large public hotspot.

[edit] MTik Compatibility

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disable

It activates a beta WDS compatibility with Mikrotik RouterOS. It's almost useless. Only use it when you're testing stuff from DD-WRT or using Mikrotik RouterOS.

[edit] Network Configuration

Available Settings: Unbridged, Bridged

Default Setting: Bridged

Recommended Setting: Bridged

This setting controls if the wireless interface is "bridged" with the LAN ports. Bridged meaning a client on the wireless interface and a client on the Ethernet LAN interface are on the same network on the same subnet. Unbridged allows you to "separate" the WLAN (wireless LAN) by giving it its own subnet and even its own DHCP server. If you want a unbridged interface, you are better off creating a VAP instead of unbridging the main interface.

[edit] Wireless Security

[edit] Security Mode

Available Settings: Disabled, WPA Personal, WPA Enterprise, WPA2 Personal, WPA2 Enterprise, WPA2 Personal Mixed, WPA2 Enterprise Mixed, RADIUS, WEP

Default Setting: Disabled

Recommended Setting: WPA2 Personal or WPA2 Personal Mixed (inc Enterprise)

Depends on what your network security needs are, for more advanced security like RADIUS etc. Do NOT use "WPA" (aka WPA1) only or WEP, they are weak ESPECIALLY WEP! Can be cracked easily, in seconds for the latter, they also go against the IEEE 802.11n/ac specification & will usually force your link rates down to 802.11a/g speeds (54 Mbps!) This is one of the leading causes for users not knowing why they aren't getting N or AC speeds with DD-WRT.

Security from weakest --> strongest goes in the following order (not counting enterprise):

Unsecured --> WEP --> WPA+TKIP --> WPA+AES --> WPA2+AES

[edit] WPA Algorithms

Available Settings: AES, TKIP+AES, TKIP

Default Setting: Disabled

Recommended Setting: AES

The core of your wireless security strength besides having a complex password & works hand in hand with security mode, to follow IEEE 802.11n/ac spec, you MUST use WPA2 Personal or WPA2 Personal Mixed + AES (inc Enterprise) do NOT ever, ever, use TKIP or even TKIP+AES or you will be forced down to a/g speeds along with your wireless security being weak. If you have some older devices that don't support WPA2, only WPA & WEP, don't worry & do NOT use WEP! Use WPA2 Personal Mixed + AES, this still follows spec & allows full speed link rates with the best security possible. By default all wireless devices always connect using their strongest supported security, ie if your network has all WPA2 AES supported clients, but you have a PSP that only supports WPA AES, your other clients will still use WPA2 AES while the PSP uses WPA AES, no problem. Having this set to TKIP or TKIP+AES in conjunction with incorrect security mode noted above, is THE leading cause of not getting n/ac speeds in DD-WRT. See this link for more in depth info about AES which stands for Advanced Encryption System.

[edit] WPA Shared Key

Available Settings: Anything

Recommended Setting: Whatever you want, make it rememberable & difficult/random

This is your network password, make it complex coupled with WPA2 AES, you'll have the best security available, theres no WPA3 AES (yet)! The "unmask" checkbox toggles between hiding your password with the traditional dots, or displaying it in clear text.

[edit] Key Renewal Interval

Available Settings: 1 ~ 99999

Default Setting: 3600

Recommended Setting: 3600

In seconds, which is 1 hour by default for almost every router firmware out there including stock (3600 sec = 1 hr), is how often the wireless encryption key is changed, this is NOT your password changing, this is within the core of how wireless security functions & is a instant seamless silent event that happens with all connected clients every hour by default. Most users have no need to change this setting, its purpose is to further thwart off potential hackers & thieves by having the encryption key change frequently, WPA2 AES is extremely hard to crack & in the event a stranger in range was pulling their hair out trying to break in to your network, once the key refreshes they'll have to start all over again with a different encryption key to defeat.