To change the port number on your Remote Desktop you must right click on the icon and select "edit" as you can see below.

Once this is clicked it will open the Remote Desktop and you can see the connection details for the server, circled in Red is the 4 digit port number.

At the moment it should be 3389, to get your Remote Desktop working again change this port to the one provided to you.

Once you have changed this number, if you click "Save" this will update your Remote Desktop and should now connect as normal.