Radar Detection never goes away

Installing and Using OpenWrt
1

Hi there,

First of all, I am new to OpenWRT.

I've been reading a bit about DFS etc, so in my understanding radar detection should clear the channel in a few minutes. In my case, Radar Detection just never goes away. Routers stayed on overnight. Nothing about the actual radar detection in the logs

                    * 5230 MHz [46] (20.0 dBm)
                    * 5240 MHz [48] (20.0 dBm)
                    * 5260 MHz [52] (20.0 dBm) (radar detection)
                    * 5280 MHz [56] (20.0 dBm) (radar detection)
                    * 5300 MHz [60] (20.0 dBm) (radar detection)
                    * 5320 MHz [64] (20.0 dBm) (radar detection)
                    * 5500 MHz [100] (20.0 dBm) (radar detection)
                    * 5520 MHz [104] (20.0 dBm) (radar detection)
                    * 5540 MHz [108] (20.0 dBm) (radar detection)
                    * 5560 MHz [112] (20.0 dBm) (radar detection)
                    * 5580 MHz [116] (20.0 dBm) (radar detection)
                    * 5600 MHz [120] (20.0 dBm) (radar detection)
                    * 5620 MHz [124] (20.0 dBm) (radar detection)
                    * 5640 MHz [128] (20.0 dBm) (radar detection)
                    * 5660 MHz [132] (20.0 dBm) (radar detection)
                    * 5680 MHz [136] (20.0 dBm) (radar detection)
                    * 5700 MHz [140] (20.0 dBm) (radar detection)
                    * 5720 MHz [144] (20.0 dBm) (radar detection)
                    * 5745 MHz [149] (disabled)

Netgear R8000

Please advice.

Thanks

2

It is showing that on those channels it will need to do an initial radar scan first before starting transmission, and that it will monitor for radar signals the whole time and vacate the channel if detected.
That status doesn’t disappear.

3

Okay...well...those channels are not available for selection, and the 2nd 5G radio just shows them as disabled.....

4

The DFS channels probably won't be usable until you set the country code and it has been documented/reported that some systems have those channels disabled by the manufacturer with no way for OpenWrt to enable them. If you want to try to use DFS channels the following may help. Ignore it if you don't want to try them. Note that if radar is detected, your WIFI radio will immediately shut down and wait quite a while before retrying. You can add settings so that it will fail over to alternate channels when that happens but it is disruptive to active data streams.

I live in the US so when I set option country 'US' for the 5g radio config it worked like a charm after committing the change and rebooting. Try it with setting the country code for your country. There is a setting for that in the web interface as well. I'm away from my setup so I can't give specifics now.

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5

Tried that as well. Channels on radio0 are still limited to 149 - 165

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6

Okay they did actually show up on the other band. Making progress.
So apparently most of the channels are available for selection on one interface (although DFS channels don't seem to work anyways) but the other one has just a few. Wondering if that's because only one of the interfaces is DFS-enabled...

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7

What device? That would be helpful.

If you’re talking about a device with dual 5GHz radios, some (most?) of them are limited to one radio being in the high band and the other in the low.

2 Likes
8

Netgear R8000, it was mentioned above.
Thanks.

9

So it is like i said above, the 2 radios are for different ranges.
See also: Netgear R8000 radio0 problem, 5GHz channels missing - #10 by yajifu

2 Likes
10

Thanks for clarifications.
If I understand correctly, there's nothing I can do about it other than getting different pair of routers.

12

Few days latter, the question still stands: Why DFS channels are not cleared for use?

  1. Country is set to US
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#2
country 99: DFS-UNSET
        (2402 - 2482 @ 40), (6, 20), (N/A)
        (2474 - 2494 @ 20), (6, 20), (N/A)
        (5140 - 5360 @ 160), (6, 20), (N/A)
        (5460 - 5860 @ 160), (6, 20), (N/A)

phy#1
country 99: DFS-UNSET
        (2402 - 2482 @ 40), (6, 20), (N/A)
        (2474 - 2494 @ 20), (6, 20), (N/A)
        (5140 - 5360 @ 160), (6, 20), (N/A)
        (5460 - 5860 @ 160), (6, 20), (N/A)

phy#0
country 99: DFS-UNSET
        (2402 - 2482 @ 40), (6, 20), (N/A)
        (2474 - 2494 @ 20), (6, 20), (N/A)
        (5140 - 5360 @ 160), (6, 20), (N/A)
        (5460 - 5860 @ 160), (6, 20), (N/A)
  1. No mentions of radar detection in the log
  2. iw list shows [ DFS_OFFLOAD ]: DFS offload. In my understanding, with this feature kernel takes control over DFS channels availability regardless of the userspace
  3. DFS channels are available for selection, but AP won't come up:
 * 5170 MHz [34] (disabled)
                        * 5180 MHz [36] (20.0 dBm)
                        * 5190 MHz [38] (20.0 dBm)
                        * 5200 MHz [40] (20.0 dBm)
                        * 5210 MHz [42] (20.0 dBm)
                        * 5220 MHz [44] (20.0 dBm)
                        * 5230 MHz [46] (20.0 dBm)
                        * 5240 MHz [48] (20.0 dBm)
                        * 5260 MHz [52] (20.0 dBm) (radar detection)
                        * 5280 MHz [56] (20.0 dBm) (radar detection)
                        * 5300 MHz [60] (20.0 dBm) (radar detection)
                        * 5320 MHz [64] (20.0 dBm) (radar detection)
                        * 5500 MHz [100] (20.0 dBm) (radar detection)
                        * 5520 MHz [104] (20.0 dBm) (radar detection)
                        * 5540 MHz [108] (20.0 dBm) (radar detection)
                        * 5560 MHz [112] (20.0 dBm) (radar detection)
                        * 5580 MHz [116] (20.0 dBm) (radar detection)
                        * 5600 MHz [120] (20.0 dBm) (radar detection)
                        * 5620 MHz [124] (20.0 dBm) (radar detection)
                        * 5640 MHz [128] (20.0 dBm) (radar detection)
                        * 5660 MHz [132] (20.0 dBm) (radar detection)
                        * 5680 MHz [136] (20.0 dBm) (radar detection)
                        * 5700 MHz [140] (20.0 dBm) (radar detection)
                        * 5720 MHz [144] (20.0 dBm) (radar detection)
                        * 5745 MHz [149] (disabled)
                        * 5765 MHz [153] (disabled)
                        * 5785 MHz [157] (disabled)
                        * 5805 MHz [161] (disabled)
                        * 5825 MHz [165] (disabled)

Mon Sep 19 12:39:31 2022 daemon.notice netifd: Wireless device 'radio2' is now down
Mon Sep 19 12:39:32 2022 daemon.notice netifd: radio2 (4664): command failed: No error information (-524)
Mon Sep 19 12:39:32 2022 daemon.notice netifd: radio2 (4664): command failed: I/O error (-5)
Mon Sep 19 12:39:33 2022 daemon.notice hostapd: Configuration file: /var/run/hostapd-phy2.conf (phy wlan2) --> new PHY
Mon Sep 19 12:39:33 2022 kern.info kernel: [22435.648219] br-lan: port 7(wlan2) entered blocking state
Mon Sep 19 12:39:33 2022 kern.info kernel: [22435.653560] br-lan: port 7(wlan2) entered disabled state
Mon Sep 19 12:39:33 2022 daemon.notice hostapd: wlan2: interface state UNINITIALIZED->COUNTRY_UPDATE
Mon Sep 19 12:39:33 2022 kern.info kernel: [22435.659359] device wlan2 entered promiscuous mode
Mon Sep 19 12:39:33 2022 daemon.notice hostapd: wlan2: interface state COUNTRY_UPDATE->HT_SCAN
Mon Sep 19 12:39:34 2022 daemon.notice netifd: Wireless device 'radio2' is now up
Mon Sep 19 12:39:34 2022 kern.err kernel: [22436.890616] ieee80211 phy2: brcmf_cfg80211_start_ap: Set Channel failed: chspec=58218, -52
Mon Sep 19 12:39:40 2022 kern.err kernel: [22442.890461] ieee80211 phy2: brcmf_cfg80211_start_ap: Set Channel failed: chspec=58218, -52
...

Routers have been on for a while - no change whatsoever.

Questions:

  • Is there any kind of command that could be send to the kernel to force radar scan in order to hopefully clear the channels?
  • Is there an option to disable DFS_OFFLOAD so that DFS would be handled at the user space (assuming OpenWRT supports that) ?
  • Kernel patching maybe?

Thanks!