[FS#506] BT Home Hub 5: 5g WiFi jumps to channel 36 and stops working if stopped and restarted

[LEDE Bugs]

The following task has a new comment added:

FS#506 - BT Home Hub 5: 5g WiFi jumps to channel 36 and stops working if stopped and restarted
User who did this - Arjen de Korte (arjendekorte)

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1) Irrelevant. DFS is not about congestion, it deals with radar pulses. If it doesn't find something that resembles a radar pattern, it won't switch.

2) Ditto. If no radar is detected, DFS doesn't cause channels to switch.

3) In my setup, the device only has a maximum of about two hours of 5 GHz traffic per day (and sometimes not even that for weeks on end). The last time I saw it switching from the configured channel, was when I had it on Ch 120 just after the DFS patches went mainstream in OpenWRT (something like two years ago). After switching to Ch 104, it never switched channels again. I very much doubt that a lack in traffic will cause this.

4) This may be purely coincidental. Assuming you're seeing radar pulses, it may be active only during a few hours during the night. What do the dfs_stats tell you? Is a radar detected?

# cat /sys/kernel/debug/ieee80211/phy1/ath9k/dfs_stats
DFS support for macVersion = 0x1c0, macRev = 0x4: enabled
Pulse detector statistics:
    pulse events reported    :       1040
    invalid pulse events     :          3
    DFS pulses detected      :        627
    Datalen discards         :          0
    RSSI discards            :        410
    BW info discards         :          0
    Primary channel pulses   :         17
    Secondary channel pulses :        579
    Dual channel pulses      :        441
Radar detector statistics (current DFS region: 2)
    Pulse events processed   :       1059
    Radars detected          :          0
Global Pool statistics:
    Pool references          :         14
    Pulses allocated         :         67
    Pulses alloc error       :          0
    Pulses in use            :         20
    Seqs. allocated          :         55
    Seqs. alloc error        :          0
    Seqs. in use             :          2

5) Does it also block, if you change to a different channel in /etc/config/wireless before starting WiFi again?
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=506#comment1784