The database server is on a separate server so you will need to use the server IP in your connection string.
Here is an example of what the connection string should look:
Driver={SQL Server};Server=your_database_server_ip;Database=some_database;User ID=some_user;Password=some_password;
IPs of our MSSQL servers are listed below:
208.101.11.244 (All new accounts use this server. Hence, if your account was setup recently, you need to use that IP in your connection string)