I have used the following guides with no luck:
http://www.rayheffer.com/953/building-a-remote-desktop-gateway-rdg-rd-gateway-server/
We have MS TMG 2010 on Server 2008 R2 Standard. All we would like to do is allow home users (who have an AD account at work) connect to their own workstation at work over RDP. Essentially they would be using mstsc.exe from their home computer to do this.
We have to go over port 443 due to filtering of port 3389 on the ISP side. We don't want to use SSTP as Windows XP users won't be able to connect. So I decided to install RD Gateway on the server. We do want to use the same server as where TMG is on.
But even using the guides above, when we try to connect from home, we get:
Your computer can't connect to the remote computer because the remote desktop gateway server is temporarily unavailable.
We are getting so confused with setting this up and have spent weeks on it.
Sometimes we get:
Your computer can't connect to the remote computer because the Remote Desktop Gateway server address requested and the certificate subject name do not match. Contact your network administrator for assistance.
I have only installed the Remote Desktop Gateway role, not the Web Access one as we only want to use mstsc.exe from home.
Best Answer
Well, first of all don't use port 443, that's the default SSL port. If you use a different port for RDP (your explanation doesn't ring true with me - I've never seen an ISP that filters port 3389, but I suppose anything's possible), then you should at least use a port that's not also in use by a common protocol or service.
Second of all, TMG lets you configure a Remote Access VPN. This is what you probably should be doing instead of, or in addition to setting up a Remote Desktop Gateway.
Third, sounds like you'd benefit from hiring an experienced Windows SA to set this up for you, even if only on a contract or consultant basis.