Been banging my head for weeks. It's to ask for help.
I have an SBS 2011 server. It has been running RWW with TSGateway just fine for more than a year, them in mid march of 2013 we lost the ability to RDP to computers on the LAN through RWW.
Let me list what does work:
Computers -> Connect: Server (the sbs server)
RDP from any LAN pc to any LAN pc using name or IP
RDP from the SBS console to any LAN pc using name or IP
What does not work:
Internet pc -> RWW -> Computers Connect
Internet pc using mstsc and setting the RD gateway in the advanced page
Based on the above, noting the mstsc test, I think it has to be the ts gateway itself. Since I can RDP to the SBS server from outside, and I can RDP to any LAN computer from the SBS server, the "handshake" between the WAN and LAN side of the server seems to be the only point of failure.
Please ask any questions. I'm able to try anything. I did run the "connect to the internet" wizard too.