|Wrong one. I'll post the correct link for you below:|
On the page that opens up, give a quick read and click on the "Proceed" button to get to the actual scan page.
I would suggest you click on the "User specified custom port" and enter 3389 there. Alternatively, you could click on the "all service ports" button and test a bunch of them.
I would suggest getting the external interface of the server itself working on 3389. If however you need to go through the "back door" (ie: in through the router) you can verify the router's external IP address at "what's my ip" (google that) so you can be sure you're attempting to connect to the correct IP.
I will repeat again my misgiving's at having this server sitting out on the internet the way it is. If your SOHO Router has a DMZ feature, I'd enable it and put the server in the DMZ.
I'm curious how you have this network setup. Do you have two separate internet connections, one to the server, one to the router? Please describe your setup for me. Also, if you could supply me with the make/model of your SOHO Router, I would appreciate it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.