I am a adamant user of Remote Desktop service provided by Windows Server 2008 and 2008r2.
I started with Windows 2008 server, upgraded to 2008r2. Everything worked same as before, including gateway and RDP.
I had a static IP with Roadrunner, then switched service to dynamic IP and started using DynDNS.com to track my network IP.
This is when several problems occurred.
Problem 1: (could not RDP to VM’s through internet or locally - issue with FQDN - Fully Qualified Domain Name)
First thing needed was to reconfigure router (Dlink DIR655).
-changed static setting to dynamic.
-updated firmware to 1.33NA.
-no DNS server settings (reset to 0.0.0.0)
-no mac address cloning (reset to 00:00:00:00:00)
-reset wireless settings back to original (forgot to write down settings before firmware update, but found my old notes 
-configured advanced/virtual server for gateway and RDP accesses both.
-without static IP, my FQDN was now coming up with server.socal.rr.com and causing name resolution problems. I resolved this problem after much research and several attempts including running CMD and ipconfig /registerdns. Not sure what fixed local FQDN problem, but it got resolved. (Test with IP number of RDP PC to see if you can connect with IP number if FQDN is the culprit.)
Problem 2: (could not connect via internet to gateway server)
-I did a lot of testing and changes, research on web, tried several suggestions. Connecting to gateway finally resolved, but could not connect to RDP through gateway, which became problem #3. I will come back and add to resolution to problem 2 if I can remember the steps that resolved that issue.
Problem 3: (RDP from gateway screen was giving invalid certificate error.)
-tried resetting self signed certificate several times. Did not resolve issue. Connecting to gaetway gave me the server certificate, but in the RDP session it gave certificate error. I noticed that the domain name in the certificate error was for an internet domain name that I had previously used from my web site when I created a redirect to my gateway server for convenience. This was very puzzling. Found almost no information on this scenario. However, one link gave me a clue (insert link here). The problem was that the domain name was not providing the correct certificate validation and thus RDP was failing. More research led me to IIS.
-Noticed that a RDWeb folder was added to IIS. Originally, the gateway server was using TS folder in IIS. So instead of connecting remotely to https://server.com/ts I tried to connect to https://server.com/RDWeb and got error. Tried http://localhost/RDWeb and that worked. Issue was in binding for https in IIS for Default Web Site. Was missing certificate! Added the server’s self signed certificate and connection was successful.
Summary:
My static IP was working but dynamic IP started the name resolution problem. That resolved led me to gateway connection problem. That resolved led me to certificate problem. The fix was here was to switch from using TS/gateway to using RDWeb/gateway. This was because I upgraded my server from 2008 to 2008r2. Did not find any info on this being an issue on TechNet, unfortunately. would have saved a lot of time. I found this out by creating a new Hyper-V Vm on server 2008r2 and comparing settings between the new gateway (which worked) and the older gateway which was not connecting. 10 days and many hours later, all is working (so far).
Will update this blog with new info if it is necessary.
