We have 2 5508's, 2 7500's, and 12 4400 series pan controllers. All but one is getting flooded with radius failed to respond. We have three radius server configured for AD authentication. One for BYOD, one for machine authentication and one for group authentication. I have not changed anything on the WLC's and its been fine for months. This started last week and there are clients getting timeouts when connecting.
Go through the below link and make sure, what are the prerequisites for radius server to reorder.
posted below ans :-
Increase the radius timeout value.
collect debug client from WLC
Also capture the wireshark messages between WLC and radius.