Symptom
AP stops sending Beacon frame on one of the radio either 2.4 or 5Ghz.
Clients will not see the SSID name on their available Wi-Fi list and will not be able to associate as a result.
Conditions
AP9120, AP9115, AP9105 running 17.3.x.
17.6 or 17.9 are not affected by this bug. It's 17.3 specific bug.
It also affect AireOS since this is AP internal bug. 8.10MR7 or earlier may hit this issue. 8.10MR8 has a fix.
Workaround
You can recover the problematic situation by resetting the AP radio(s).
Following CLI, or GUI will do the work.
AP specific method:
C9800-WLC#ap name YOUR_AP_NAME dot11 {5ghz|24ghz} shutdown
C9800-WLC#ap name YOUR_AP_NAME no dot11 {5ghz|24ghz} shutdown
OR
Entire radio band method (Warning, your entire 2.4GHz or 5GHz network should go down):
C9800-WLC(config)#ap dot11 {5ghz|24ghz} shutdown
C9800-WLC(config)#no ap dot11 {5ghz|24ghz} shutdown
Further Problem Description
AP9105, AP9115, and AP9120 running 17.6 or later (or AireOS 8.10MR8 or later) release has new radio firmware which does not have the root cause of this bug. Hence you'll not hit by this bug when you're running 17.6 or later (or AireOS 8.10MR8 or later) releases.
If you did see AP stopping Beacon when you're running 17.6 or later (or AireOS 8.10MR8 or later), it will not be caused by this bug but other issues.
