Symptom
C9105/C9115/C9120 AP stops allowing new associations on any of the configured SSIDs on a specific radio interface (2.4GHz, 5GHz, or both).
By capturing OTA, or collecting AP client trace log on the specific AP, you will notice the AP is not responding to 802.11 Authentication frame which was sent from some specific clients.
This situation can occur if you hit this defect, or if the specific clients were put into exclusion list which is enabled per policy profile by default. If you disabled exclusion list on the policy profile and still see the AP is not responding to Authentication frames sent from specific clients, you are most likely hitting this bug.
Conditions
Affected WLC: Any WLC
Affected AP: C9105 series, C9115 series, and C9120 series.
Not affected AP: C9130 series, C9136, CW9166, CW9164, and CW9162.
Affected SW version:
IOS-XE 17.3.3 or earlier
AireOS 8.10MR5 or earlier
Environment: High density environment will see the symptom at most. For example, around 200 unique Wi-Fi clients will associate to a single AP within an hour. Normal situation where around 200 clients associate to many APs, say, 10 APs, and the each AP having 20 or so clients will not be a problem.
Workaround
Disable the specific 5GHz or 2.4GHz interface on the specific AP. And then enable it again. Disabling and enabling whole 5GHz/2.4GHz radio network for all APs will also recover the situation temporally. No AP reboot is required to recover the problematic status.
If the AP located in high density environment reached to around 200 clients in a short time, then the symptom will become visible again. You need to repeat the disable/enable radio every time when you hit this issue.
Further Problem Description
By using DNA Center, you can monitor the clients trend. i.e. The number of associated clients per AP.
The number will be increased as time goes, sometimes it can be decreased, however it will reach 200 at the end of the day. If you did not see the number is decreasing from 200, then you can decide this defect is triggered.
