Help connecting External SQL Express to Power BI

Hey,

I need to access an external SQL Express server but am getting and error message;

"Details: "Microsoft SQL: 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 wait operation timed out.)""

Annonymised details as follows;

IP: 11.111.11.11

SQL Server –**-**-***\SQLEXPRESS 

I read somewhere that I need to put a port of 1433 but I'm not sure where I'm going wrong.

I have entered the username and password correctly

Thanks,

J