CSCvx56223 - Cisco C9120 AP stops allowing new associations on SSIDs

[Johnny]

Hello CISCO Community, 

I am experiencing a rather odd situation with our wireless environment. We have recently upgraded our wireless controllers, CISCO Catalyst 9800-40, to the 17.9.5. 
After this upgrade we started experiencing loss of associations on our 9120 model access points. This occurs for only one of our locations with approx. 25 or so access points. The quick solution that we have found is to reboot the access points. I do have a case open with CISCO, I am just curious if anyone else has seen this issue. If so, what did you do to remediate the problems?

[tomsankey1996]

Hi Johnny,

Do you know what is triggering this behavior? As we have similar strange behavior, in which our sites failover to the backup connection and the CAPWAP tunnels between AP and WLC move into a NULL state

[Johnny]

I do not know what is causing this. I have opened a case with TAC. The CAPWAP tunnel appears to stay up and connected to the controllers as I can access them during the time of reported issues. 

[tomsankey1996]

Hi Johnny,

Do both the CAPWAP data and management tunnels stay up?

Run the following on the WLC next time you have the issue: show wireless dtls connections 

[Leo Laohoo]

---

 wrote:@Johnny
If so, what did you do to remediate the problems?

---

1.  Do not use 17.9.X.  Use 17.6.X or 17.12.3 but avoid 17.9.X.

2.  Reboot the APs daily.