Can't set mode "2.4 ghz/40Mhz" for router

Hi, wifi work fine for 2.4ghz/20Hhz - max speed 150Mhz. But I can’t set mode 2.4 ghz/40Mhz - max speed 300Mhz. Why ? Client support this speed, but not work for turris omnia.

Automatic drop.
Enable ht_coex and noscan options in /etc/config/wireless

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How to do it exactly, please? In the file is no such commands like ht_coex or noscan.


40mhz channel is meant to be only used by people who know what they are doing, because it will probably make the wifi experience worse for your neighbors.

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@bdfy will realize why it’s falling down from 40 to 20 automatically :wink:

option noscan '1'

in wifi-device section

Is the syntax the same for ht_coex?

Could you please elaborate a little more, what these options do? Thanks a lot.

Check openwrt wiki…

This is quite “hypocritical” statement, when all the mainstream (low-end) Chinese devices are using 40 MHz channels out-of-the box (like TP-Link, Tenda, etc.).

In my neighbourhood, there are something like 10 wifi networks that my mobile can see, and 6 (!) of them are using 40 MHz channel. Their owners are typical BFUs (“it’s in the power, it’s blinking, so it should be working…”).

Only I, with this high-end, super-tech and super-expensive Turris Omnia, am NOT able to setup 40 MHz channel, so my wifi is slow. That’s really “satisfying” to know, that paying $400 for TO makes your wifi the slowest among all other wifis in your neighbourhood, because “you need to know what you are doing” and it is not sufficient to set the option on the web-interface as one would expect"… and all of this just “to make the wifi experience for your neighbours better” – great! :-\

Do you think that those chinese manufacturer/my neighbours asked for my wifi experience, when they enabled 40 MHz channels on those routers?

Thanks, here are the links (for other viewers):

  1. OpenWRT - Wireles Configuration / Device Options

  2. OpenWRT - 40 MHz channel width (up to 300 Mbps)

I don’t think so. Usually it is auto, 20 or 20/40 in default.

It doesn’t mean it is set to 40 only. Scan is performed when device goes up and at it is possible that during this time was no interference detected. Very often after power outage in neighbourhood fast booting APs gain 40Mhz and slow APs just 20.

You are able to set 40MHz. Probably you can see 300/300Mbps link speed but how fast/ reliable is questionable. Even if in your neighborhood will be everybody on 20MHz width you will most probably experience problems and the real speed won’t be higher - mainly during day peeks when channels are utilized by clients.
If you will be in the middle of nowhere then yes - 40MHz is advantage.

Don’t forget that there are just 2 non-overlaping channels in 2.4GHz for 40MHz width and 3 for 20MHz (okay 4x20 with small overlaps in most countries). If just 2 APs will set 40MHz you’re out free channels.
Then you have bluetooth, microwave ovens, wireless keyboards, USB3.0,… operating/ interfering in 2.4GHz which you can see by spectral scanner only.

In my experience with many routers and many environments 40MHz width (in 2.4GHz) is no gain but pain. Even if there are just 20MHz channels in neighborhood it’s almost impossible to find free channel or not utilized by traffic (active-but-dead).

So - you’re free to do whatever you want. I just tried to explain that in 99.9% there is no advantage to go wide and that there is smart reason why your radio is dropping to 20MHz even when you set 40.

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