Hi Criszhan,
Thank you for the response. In Report Builder, I'm trying to set the new connection properties to the following:
Data Source = Microsoft SQL Server (sqlclient)
Server name = <The name of the SQL server that is only accessible via VPN since it is on a 3rd party network infrastructure>
Logon to the server = I use 'Use SQL Server authentication'
Username = Administrator
Because it is on a 3rd party's network and only accessible via VPN, when I perform a test connection, it cannot find the SQL database and in the database name, there is no database instance listed.