In Management Studio (after connecting to the server) open "Management" and then open "SQL Server Logs". Open the "Current" log and scroll to the bottom of the log. Look for the text "Server is listening on .....####'
Because one of the ports, usually the lower number (ie. 1433), is for outside connections coming in, while the other port is for dedicated admin connection support, usually the next port number (ie. 1434).
So to answer your next question you haven't asked yet; you want to give your clients the "lower number" port 1433.