Have just set up a Server 2008 R2 machine with Remote Desktop Services. It's all running on the one server, just for a couple of applications, which works fine locally and when using Remote Desktop Web Access on the local network.
However, when accessing it over the Internet, you can log on to RD Web Access fine, but when running the RemoteApp you get the message:
The remote computer could not be found. Please contact your helpdesk about this error.
I have registered the external name in dns and allowed it thru my firewall.
I have tried different setting on terminal server settings within remote apps manager. I tried using external ip address, external dns name. I am not using a remote gateway, the terminal servers are not in a farm.