Directory Sync Pro Service will not start (4329002)

When trying to start the service you get

The BinaryTree Directory Sync service failed to start due to the following error:
The service did not respond to the start or control request in a timely fashion.

In the Windows application log you are seeing

SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - The remote computer refused the network connection.)

This is a SQL connection issue and the service will not start until the connection issue is resolved.

Check that you are able to access the SQL DB with the service account from the Dir Sync Server