Refer to the exhibit. Why did Client 00:25:84:61:92:7d not get a response from the RADIUS server?

If the RADIUS server rejected the username, it would typically send a specific 'Access-Reject' message back to the wireless controller, rather than providing no response.

RADIUS clients (like the wireless controller) and servers use a pre-shared secret key to authenticate each other and encrypt certain parts of their communication. If the shared secret keys on the controller and the RADIUS server do not match, the RADIUS server will silently discard the incoming authentication request packets from the controller, resulting in no response being sent back.

If there was no IP connectivity, the wireless controller would not be able to send the RADIUS request to the server at all, or the request would time out without reaching the server for processing.

A disagreement on the EAP type would usually result in the RADIUS server sending an 'Access-Challenge' or 'Access-Reject' message to the controller, indicating a negotiation failure, not simply no response.