I'm helping a client, and almost all the APs are flagged with a 100% connection failure. The event log for the AP reads:
(WARNING) AP NAME flagged health  because it crossed the threshold .
(INFORMATIONAL) AP NAME flagged health  because it crossed the threshold .
I can find nothing that would be causing this. Clients also don't seem to be having trouble using the network, though WiFi Calling seems to struggle with dropped calls. (not sure if related).
We made sure that there is no co-channel interference (Smaller channel size, set a static plan, and ended up disabling background scanning (some people said this could effect VoWiFi calling).
Any input or recommendations would be greatly appreciated. I could find very little on the topic except for posts saying that under 3.6 connection failures were being falsely reported. This however, is occurring on 5.0.
Below is a graph of what we are seeing. The same behavior is seen on the 5 Ghz. APs are all 610s, with one 710.
We got a similar issue when a customer upgraded his vSZ to the 3.5 code, connection failures went to the sky. In our scenario this issue was because there was a bug with the access control lists, mac address access list to be specific. We disabled the access list and the issue was fixed as a workaround. However, the issue was fix when we upgrade again to a newer version of the 3.5 code.
Your case could be something else, it's better to have a ticket opened with support team, but just wanted to share my experience.
Have you had any success with this issue, we are also running vSZ5.0 with the exact same issue. In our case this points to a high rate of authentication failures, but I have no idea how to troubleshoot further ?