Hard to come back to DFS channel

[sergi_dupe]

I have an AP122 allowed to work on DFS channels.

Usually AP selects channel 136 because it is the only one transmitting on that channel (0 interferences from other APs nearby).

However, after detecting radar signals AP does not come back to that DFS channel after several days or even weeks. Logs keep saying this: “ah_dcd: wifi: [DFS-dcost] wifi1: Invalid channel 136” after radar signal disappears.

I thought that once radar signals are not detected anymore, AP would come back in a matter of minuter/hours.

Any hint?

Regards

[w1f1n00b]

@Paul Wang, but unless they’ve changed the default, background scans (acsp) are set for every 10 minutes.

@sergi.dupeyou can confirm background scans via cli with “sh int wifi0” or “sh int wifi1” and look for backround scans details (or use “sh int wifi0 | inc bgscan” to filter just the relevant info

Following as I’m just starting to use DFS channels and am curious what to look out for.

[Paul_Wang]

Until the next scheduled ACSP scan happens, it's the expected design that the AP will not switch back to the original DFS channel after the radar signal is detected.  But if you enable "Dynamic Frequency Selection > Enable manual channel selection return" in the radio profile (CLI:  radio profile <string> dfs static-channel) and configure a static DFS channel, the AP will try to switch back to the original DFS channel after waiting for 30 minutes following the last channel change caused by the radar signal detection.