This counts Access-Reject responses received from this RADIUS server, again including both valid and malformed rejects. A sustained rise in this counter, especially right after a password policy change or certificate rotation on the supplicants, tells an admin that credentials or EAP method mismatches, not network connectivity, are the reason 802.1X clients are failing to get onto the network via this server. For example, if this counter jumps from near-zero to 200 in the hour after a helpdesk-wide password reset, the spike is most plausibly users authenticating with stale cached credentials rather than a RADIUS server outage.