First thing first. RDP to the server, and then try to RDP to the client. Can you connect? If I read your post correct, your unable to do it. Make sure that Remote connection is enabled on the client. Right click my computer > properties > remote settings > Allow remote connections. Also, if your running a firewall, eiter disable it or allow exception for the port and service. You need to be able to connect internally before you connect externally. Once your able to connect to the client, you can then change the RDP listening port and then make sure you forward the port on the router to the client name or ip address if your using a static ip address. Once you have chosen your port, open RDP Client and the put in your WAN ip address followed by the port you assigned the client ex. 123.45.67.89:3390, you must have the trailing :3390 to connect or it will try logging into the server.
