[Server Name or IP Address],[Port] is an invalid or loopback access. Specify a valid server address.

Recently I was installing SharePoint 2010 and the Configuration wizard failed giving me the below error

Failed to create the configuration database.

An exception of type System.ArgumentException was thrown. Additional exception information: [Server Name or IP Address], [Port] is an invalid or loopback access. Specify a valid server address.

We had a hardened environment where only a specific SQL port was made available.

On the Specify Configuration Database Settings screen, I entered the Database server in the below format (Database Server Name followed by a coma and the port number that was made available)

Database server: DATABASE-SERVERNAME,1581

Database name: SharePoint_Config_test

The fix

Enter in the below format(if there is only one instance of SQL in the database server) (append '\MSSQLSERVER' after the Database Server Name followed by the coma and the port number)

Database server: DATABASE-SERVERNAME\MSSQLSERVER,1581

Database name: SharePoint_Config_test