Ok, re-trying this question, with more accurate information.
I have a client with a RemoteApp and RDGateway services facing the public internet. The conditions are these:
1) Able to log in successfully to the initial RD Web Access web page from any external location. No issues are being reported internally.
2) Able to launch published apps successfully only from some external locations.
3) Using same user credentials, launching published apps from other locations results in "This computer can't connect to the remote computer because the Terminal Services Gateway server is temporarily unavailable" error.
4) From the same locations where launching a published app fails, I am able to make a direct RDP connection to the server running Gateway and RemoteApp services using the native RDP client in Windows.
5) There is no common ISP in the mix.
6) As far as I can tell, there is no CAP or RAP in effect that would cause only selective clients to connect
7) The client is using a DigiCert ssl certificate, not a self-signed cert.
8) The RD Broker service is installed and running.
Can anyone hazard a guess as to why this would be working from some external locations, yet produce the above-noted error at other sites? I will be happy to provide any additional information that mau be needed ... but I just don't know where to start looking.
Regards and thank you in advance.
Chris