The error below is reported each 5 minutes:
Diagnostic Server on servername
* Diagnostic Server - Spotlight Playback
Playback error [Connection Error]: Connecting to the instance (local) as the Diagnostic Server user failed : The TCP/IP connection to the host (local), port 1433 has failed. Error: 'null. Verify the connection properties, check that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port, and that no firewall is blocking TCP connections to the port.'.