Clients are failing EAP authentication A debug shows that an EAP handshake started and the clients are then de-authenticated. Which two issues can cause this problem'? (Choose two.)

While a mismatch in authentication type could cause failure, the phrase is incomplete, and issues B and D represent more fundamental failures in the WLC-RADIUS communication after the EAP handshake has started.

If the WLC is not added as a RADIUS client on the RADIUS server, the server will not trust authentication requests originating from the WLC, leading to authentication failures and subsequent client de-authentication because the RADIUS server does not recognize the WLC as a legitimate network access device.

A changed WLC certificate primarily affects trust for EAP methods involving server certificate validation; while it can cause EAP failure, the shared secret or WLC registration are more common initial causes for de-authentication after an EAP handshake begins.

A mismatch in the shared secret between the WLC and the RADIUS server prevents secure communication and mutual authentication between these two components. When the shared secret does not match, the RADIUS server will reject the authentication requests from the WLC, causing the EAP handshake to fail and the client to be de-authenticated.

If the WLAN is not configured for the correct EAP supplicant type, the EAP handshake might not even initiate correctly, or it would fail at a very early stage of method negotiation, rather than progressing to de-authentication after starting.