Hello. Thank you for reading this post and assisting me with this:
I have a RDS Web Access on a single Windows Server 2012 with published remote apps. All users can logon to the RemoteApps page, but only Windows 7/8 users with RDP 8.0 update (KB2592687) can actually launch the published Remote Apps. Any users trying to logon without the RDP 8 update are repeatedly prompted for their password and cannot logon.
Windows 7 users are able to install the RDP update, but this is not available for XP. I cannot imagine that Microsoft would exclude XP connections so I am sure that I am missing something.
Note: I have tested XP clients over the LAN and connections work fine. They just do not work over the internet using RD Gateway. I am testing logon using the same credentials on different clients so I have ruled out any obvious permission issue.