Radius backend incoming frame handling failed

Logged when a RADIUS backend connection cannot read or process what the server sent, for example because the server closed the connection abruptly or sent a malformed frame. The connection is closed and replaced. When an alerts block enables backend incidents, this opens or extends the backend's incident, which recovers once the pool has connections again.

Check whether the backend server restarted or stopped. If it keeps running, inspect the error and the traffic from that server.