Bug? Channel analysis not working for 5ghz

noob2023 · January 9, 2023, 2:12pm

My router is a dual band router. 2.4ghz channel analysis works fine and shows my Local Interface and others but 5ghz is only showing Local Interface. I remember this working 6 months or so ago when i set up the router. I just did an update today to 22.03.3 and decided to check. Anyone else have the same issue? Thx

slh · January 9, 2023, 9:16pm

Scanning while actively using a DFS channel isn't always possible, neither with all drivers, nor in all regulatory domains.

ThiloteE · January 10, 2023, 8:10pm

Would help, if you mentioned the name of your router.
Do not set COUNTRY=FR. Please set your actual country. There are strict regulations in many countries, and if you misconfigure your device, you could hit radar or other electronic device channels. ~~In my country, the bands for firefighters apparently sits right next to wifi, if I remember correctly.~~ Edit: I looked it up. Here, bands for firefighters are actually pretty far away from wifi channels, but I am sure someone/something will be using those frequencies ;-). There can be pretty huge fines ranging into thousands of euros, if your device illegally interferes with other bands.

onix · March 21, 2023, 7:20am

I have the same problem. Only the local channel is showing up on 5GHz. Works fine for 2.4GHz.

root@ArcherC7v5:/etc# uname -a
Linux ArcherC7v5 5.10.161 #0 Tue Jan 3 00:24:21 2023 mips GNU/Linux

root@ArcherC7v5:~# iw reg get
global
country US: DFS-FCC
        (902 - 904 @ 2), (N/A, 30), (N/A)
        (904 - 920 @ 16), (N/A, 30), (N/A)
        (920 - 928 @ 8), (N/A, 30), (N/A)
        (2400 - 2472 @ 40), (N/A, 30), (N/A)
        (5150 - 5250 @ 80), (N/A, 23), (N/A), AUTO-BW
        (5250 - 5350 @ 80), (N/A, 24), (0 ms), DFS, AUTO-BW
        (5470 - 5730 @ 160), (N/A, 24), (0 ms), DFS
        (5730 - 5850 @ 80), (N/A, 30), (N/A), AUTO-BW
        (5850 - 5895 @ 40), (N/A, 27), (N/A), NO-OUTDOOR, AUTO-BW, PASSIVE-SCAN
        (5925 - 7125 @ 320), (N/A, 12), (N/A), NO-OUTDOOR, PASSIVE-SCAN
        (57240 - 71000 @ 2160), (N/A, 40), (N/A)

phy#1
country US: DFS-FCC
        (902 - 904 @ 2), (N/A, 30), (N/A)
        (904 - 920 @ 16), (N/A, 30), (N/A)
        (920 - 928 @ 8), (N/A, 30), (N/A)
        (2400 - 2472 @ 40), (N/A, 30), (N/A)
        (5150 - 5250 @ 80), (N/A, 23), (N/A), AUTO-BW
        (5250 - 5350 @ 80), (N/A, 24), (0 ms), DFS, AUTO-BW
        (5470 - 5730 @ 160), (N/A, 24), (0 ms), DFS
        (5730 - 5850 @ 80), (N/A, 30), (N/A), AUTO-BW
        (5850 - 5895 @ 40), (N/A, 27), (N/A), NO-OUTDOOR, AUTO-BW, PASSIVE-SCAN
        (5925 - 7125 @ 320), (N/A, 12), (N/A), NO-OUTDOOR, PASSIVE-SCAN
        (57240 - 71000 @ 2160), (N/A, 40), (N/A)

phy#0
country US: DFS-FCC
        (902 - 904 @ 2), (N/A, 30), (N/A)
        (904 - 920 @ 16), (N/A, 30), (N/A)
        (920 - 928 @ 8), (N/A, 30), (N/A)
        (2400 - 2472 @ 40), (N/A, 30), (N/A)
        (5150 - 5250 @ 80), (N/A, 23), (N/A), AUTO-BW
        (5250 - 5350 @ 80), (N/A, 24), (0 ms), DFS, AUTO-BW
        (5470 - 5730 @ 160), (N/A, 24), (0 ms), DFS
        (5730 - 5850 @ 80), (N/A, 30), (N/A), AUTO-BW
        (5850 - 5895 @ 40), (N/A, 27), (N/A), NO-OUTDOOR, AUTO-BW, PASSIVE-SCAN
        (5925 - 7125 @ 320), (N/A, 12), (N/A), NO-OUTDOOR, PASSIVE-SCAN
        (57240 - 71000 @ 2160), (N/A, 40), (N/A)

root@ArcherC7v5:~#

okji1 · March 27, 2023, 4:05pm

Make sure you disable the radio you are scanning. Be in Airplane Mode (Wifi off) and using ethernet cable connection to run the channel analysis.

onix · April 5, 2023, 7:48pm

OK, but if this is required for the 5GHz channels, then it would be a bug. 2.4GHz does not require putting it in “airplane mode”. Most laptop wifi’s can surf the net and channel scan simultaneously.

slh · April 5, 2023, 10:12pm

No, it's -still- not a bug, "most laptop wifi’s" use different chipsets/ drivers and most of all, rarely are operated in AP mode (and they don't have to do anything about DFS in STA mode).

This is a classic case of "if it hurts, don't do it". Complaining about this won't change a thing - you can either accept the facts and use the given workaround or stomp your feet and wait really hard for… nothing to change.

rahlquist · April 7, 2023, 3:15pm

Thank you for the quick clear explanation as always!

dsouza · September 6, 2023, 10:44am

Well, for mt7622 Channel Analysis is still not working even after the fix below:

https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=cdc8470aecd03e6994714af092f030f209951de4

If can only see its own channel. I'm wondering if the above fix should be applicable also to mt7622.

umggc · September 20, 2023, 8:44am

I am seeing the same issue here. My router is Netgear R6220. The change was likely introduced in version 22.03. I upgraded from 21.02. The Channel Analysis function was normal with the old firmware.

umggc · October 28, 2023, 8:46am

Just an update. 5G channel analysis is working again with 23.05. Tested on Netgear R6260.

dsouza · October 28, 2023, 10:35am

Testing with the Xiaomi AX3200 / Redmi AX6S with 23.05.0, I just discovered that channel scan does not work if the router is configured with a DFS channel. See example below:

5Ghz radio configured in channel 100: channel scan does not work, shows only router's own signal:

5Ghz radio configured in channel 36: channel scan does work as expected:

So as @slh mentioned above, this seems to be a known limitation.

umggc · October 29, 2023, 5:51am

Brillient. dsouza is right. I confirm that this is not a version issue. Using DFS channel prevents channel analysis to work. Solution is to use a non DFS channel, do the scan, then pick desired channel to use.
Screenshot 2023-10-29 135339
The scan actually included dfs channels.