We've noticed that a few of our APs on the network will take the upgrade from 13.4 to 14.1.1 with no apparent issue, but when then the AP will not regain it's subscribers at all. In these cases we've had to go back and down grade the AP back to 13.4. Later we go back and do the upgrade again, and it works properly the second time.
We were wondering if this is a known issue with 14.1.1. or what.