SQL Server 2012 running on a Windows 2012 Failover Cluster Instance.
(**The cluster contains only a single node. Yes, I know that's terrible. No, it wasn't my decision....)
The issue is that at seemingly random times overnight (our period of highest network activity) SQL Server will go down.
The SQL Server error logs point to the cluster ordering it to stop:
SQL Server is terminating in response to a 'stop' request from Service Control Manager. This is an informational message only. No user action is required.
The Cluster log appears to show that it's doing so because it claims SQL Server failed:
What I'd really be interested in finding is WHY the cluster thinks SQL Server failed. Have been poking through the various failover clustering logs in Event Manager and haven't found anything yet that indicates this. Any concrete proof I can bring back to the server team and say "this is because of network" or "this is because of quorum" or whatever the reason might be, would be greatly appreciated.
UPDATE
Discovered how to view "informational" entries in the cluster event log. Not sure if this is an indicator or not, but lots of entries mentioning "Netbios: Slow Operation".
I see an entry saying "Endpoint is up" 10 seconds before first entries discussing bringing the node offline.