I have an AP25 where the 5Ghz SSID stops broadcasting after a couple of days. Power cycling the access point resolves it.
My AP12 does something similar -- it keeps broadcasting but stops rounding traffic after a couple of days [4-5] of being powered on.
Firmware issue? Heat/design issues? Both are moderately warm when in the failed state but drop temps quickly after power cycling. One is powered using POE and the other is the standard power brick.
Each of them have two SSIDs on two separate VLANs. One is a dedicated 2.4ghz SSID, the other is 5Ghz SSID. Both AP's average 15 clients or less.
I'm suffering from a similar issue with my Ap25 keep dropping network on the 5ghz band. I can't work out what is causing the problems I have a ticket open with support but not sure if I can put up with this as it's disrupting my network. My AP22s are working fine.