Netlogon backend action timed out

Logged when a netlogon backend action does not finish within the action timeout or, without one, the backend's own timeout. The time includes waiting for a free pooled connection and any connection or secure-channel setup the request needed. If the request was already using a connection, that connection is closed and the next request on its slot opens a new one.

Check that the domain controller at endpoint is reachable and responsive. Compare backend Timeouts with request rates to see whether every connection is busy before increasing the pool size or the timeout.