This counter tracks how many RADIUS Disconnect packets the device has received from source IP addresses it does not recognize as configured disconnect clients. A rising count signals that a device outside the configured client table is attempting to send disconnect (session-teardown) requests, which could indicate a misconfigured RADIUS server or a spoofing attempt against active subscriber sessions. For example, if a new RADIUS server is added to send Disconnect-Request messages but its IP was never added to the client configuration table, every disconnect it sends increments this counter instead of terminating a session.