I ran into a similar but different issue on 9130 AP's. We had high utilization on 5 GHz. The trigger in my case was limited to these conditions.17.9.4a APSP8, Zero wait DFS enabled. 40Mhz channel, Channel change or radio crash. once this happened i s...

ap dot11 {24ghz | 5ghz | 6ghz} rrm dca restart

@Stuart Patton It looks like CSCwh75431 was fixed in 17.9.4a APSP8 which just released today.https://www.cisco.com/web/software/286325254/166630/C9800-universalk9_wlc.17.09.04a.CSCwi44524.txt

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCwh75431This might be relevant for the high channel utilization no RX TX.