When you have an SQL Server which has been installed on a different port than the standard 1433 you might have trouble connecting to it if you don’t specify the port in your connection string or connection settings. This is how the syntax is, which was new to me until today. The server name (or IP) is separated using a comma sign instead of the standard colon, which are standard in URL’s and others.

So this is how you specify it:

SERVERNAME,PORT[\INSTANCE]

For example:

localhost,1389

localhost,1389\myinstance