A client cannot authenticate, down to authentication server unable to process quick enough due to CPU. What can be done to alleviate this?

Session timeout defines how long a client can remain authenticated on the network before re-authentication is required, and does not address initial authentication delays caused by a slow server.

802.11 authentication response timeout refers to lower-level wireless frame exchange timeouts, which are distinct from the timeout configured between the wireless controller and an external authentication server.

The authentication server timeout setting on a wireless controller determines how long the controller waits for a response from the external authentication server (e.g., RADIUS) before considering the authentication attempt a failure. By increasing this timeout, the controller allows more time for an overloaded authentication server to process the request and send a reply, thereby preventing premature client authentication failures caused by server slowness.