Returning a RADIUS/1.1 resource-unavailable response because the reverse-request validation queue is full

Logged when Radiator returns Protocol-Error with a resource-unavailable cause because the reverse request validation queue cannot accept another RADIUS/1.1 request. Fields show the queued request count and queue limit.

The backend is producing reverse requests faster than Radiator can select clients and validate them. Check reverse-request rates and @pre-client errors or latency before changing capacity.

Review the backend connection window, which bounds queued reverse-request validation on each connection, only when the load is expected.