Auto RF channel change - Suddenly on Multiple APs simultaneously

[TokyoKevin]

Hi.

Today we had an issue were multiple users were disconnected from the network.

When we looked at the logs, we saw that multiple APs (about 25) all had an "Auto RF channel change" logged at exactly the same second.

What could cause this, and how can we prevent it?

(Using all WiFi6 APs, 2.4Ghz disabled, high-density deployment >150APs)

[KarstenI]

Which channels were used before and to which channels did they change? Perhaps it was a DFS event?

[BrandonS]

If not a DFS event I guess the way to make sure it doesn't happen again is to plan channels manually.  One would hope whatever algorithms are used to determine when to auto update channels would limit the number of simultaneous changes, but maybe not.  It should be pretty minimal impact and not noticeable by most clients unless maybe mid voice/video call with no secondary coverage.  Did you get client complaints or just notice it in the log?

[TokyoKevin]

We did get complaints.

Some clients were disconnected but the automatically reconnected.

Some others had to reauthenticate.

It's strange.

I am seeing DFS events in the logs, but the channel changes are a mix.

One AP is changing from 40 to 36, and another is changing from 60 to 136. 

(Another changed from 44 to 48, and another from 40 to 52, and another from 100 to 104.)

For now, I have deselected DFS channels from the RF profile, and I have changed the rx-sop to -76. Max transmit power is at 10.

Is there anything else I should check?

[David4]

Happend to us as well. Total logistic facility went out of service due to our Zebra handheld refusing to stay connected.

Turns out the region settings for wifi were reset to default. The defaults heavily restrict what channels/frequencies are used for wifi.

Look into the network settings and check if the country/region is still correct.

We're still unsure why this happend.  Our IT partner had this happen at multiple customers.

[TokyoKevin]

Hi,

We checked, and the country/region is still correct.

I will check to see if there are particular DFS channels that seem to have issue. If so, I will try to disable those and re-enable the other ones. I will also disable 40 and 80MHz and leave only 20Mhz, as it is a really dense deployment.