Dropping 5ghz wifi - netgear r7800

[lenovomi]

hello,
i am not able to find out the reason of 5ghz wifi dropout each time i power on my panasonic projector,

router and projector are plugged in the same 230V power socket. Each time i power on projector 5ghz got lost ... so i need to reboot router.

any idea here?

thanks!

[hnyman]

First guess:
Your 5 GHz is configured to use a DFS channel, and your projector emits radiation / strange wireless signal on that spectrum, so that the radio thinks that a weather radar exists and shuts down.

[lenovomi]

@hnyman ah i see, and is there anything i can do with that?

i can see its set to > Channel: 104 (5.520 GHz)

[darksky]

Try channel 149 which should be above the DFS channels

[Annick]

Try channel 36

[hnyman]

If it is about radar detection, you might have DFS-RADAR-DETECTED log items about that in the system log. (But that may depend on your WiFi logging level settings)

See example in my log extract in

5 GHz WLAN craps out (upon radar detection?) - start_dfs_cac() failed

The fallback channel list should work also without that "auto". As VHT160 and DFS channel usage gets wider, I guess that more people will run into this kind of issue, so I re-opened this old thread to document the current status... I ran into this today, 5GHz wifi (at channel 100) in one of my routers dying during the night, and it took a while to notice in morning Apparently, if there is no fallback channel list provided, the 5Ghz wifi may remain dead after a DFS event. It took a …

@hnyman

Sat Mar  5 02:00:05 2022 daemon.notice hostapd: wlan0: DFS-RADAR-DETECTED freq=5500 ht_enabled=0 chan_offset=0 chan_width=5 cf1=5570 cf2=0
Sat Mar  5 02:00:05 2022 daemon.notice hostapd: dfs_downgrade_bandwidth: no DFS channels left, waiting for NOP to finish
Sat Mar  5 02:00:05 2022 daemon.notice hostapd: wlan0: AP-DISABLED

[lenovomi]

@darksky

Try channel 149 which should be above the DFS channels

using that channel i have speed issue ie slower by 100mbit on clients: (

[Annick]

Channel 149 use very low power ...

Use Channel 36 to 64

[lenovomi]

even some devices cant see ap on that channel ... arg. 149...

[lenovomi]

even 44 is slow i mean 150-200 mbit instead of ... 350

but at least seems when i power on/off projector it is still working.

[darksky]

@Annick

Channel 149 use very low power ...

Use Channel 36 to 64

Are you sure? The trend is reversed, lower power levels available for lower channels on my devices.

[p.p]

Maximum power levels depend on your regulatory domain. For EU countries, channels 149 and above are limited to 25 mW.

[Annick]

my old tread

WIFI channel 149 for France / Europe?

You could put your "channel" to "auto" and the "channels" to a very specific, hand crafted list of wifi channels. See: https://openwrt.org/docs/guide-user/network/wifi/basic#common_options That will not cause your router to constantly look for new channels to hop to, but it will at least make channel auto-detection only consider this specific list. If I'm not mistaken, the range from 5470MHz to 5725MHz should mp to channels 96 to 144. That's what the FR regulatory domain allows with enabled D…

opption country 'FR'
option channel 'auto'
option channels '36 -64 100-144'

this parameters are not visible with luci , you must therefore manually edit the wireless file

[p.p]

I am not sure what you want to tell me here? I was just trying to answer @darksky's question.