...
Using Microsoft’s TCPView from the Sysinternals suite. Can help trouble shoot troubleshoot potential issues with the network connection. In the below example, we can see Velocity performed a Sys Sent, but did not receive a message back from the SQL Server.
...
Launching SQL Server Management Studio and trying to connect to the SQL Instance can also provide useful information regarding reasons you are unable to connect to the SQL Instance.
...
If you can connect to the SQL Instance but you cannot view the Velocity database, it might be lack of permissions to the Velocity database. You should work with the SQL administrator to add the appropriate permissions to the Velocity Users group.
...
If you can connect to the SQL Instance with IP address, but not hostname of the server could indicate possible misconfiguration with DNS or Active Directory Service Principle Name (SPN).
...