Troubleshooting RDS Server 2012. Web Portal and RDP asking user to log on multiple times
I recently have had a problem with a new Windows 2012 RDS Server. I have implemented a RDS Server and a separate Gateway server for a client which appeared to work fine.
Now once fully implemented i found that it worked OK from a windows 8 Machine but on some windows 7 machines, not all. It kept going through a vicious cycle of prompting the user for their credentials, even when they were correct.
After a lot of troubleshooting, reading through Log files, Event viewer and analyzing traffic too and from the server. Seems to be a straight forward fix. The RDC client on the local machine needed to be updated to version 6.2. Before this support for DTLS needs to be installed (All of which are available in SP1 for Win 7 )

When connecting to the RDS Server either via the web portal or the RDP client on your machine it is important to ensure that you have the lates RDP client installed in Windows 7 This is because Remote Desktop Protocal 8.0 is required and only supported from version 6.2 onwards
– A symptom of not having the correct RDP version is the RDS server keep prompting for your username and password
In ordger to establish the version of RDP client running on your machine Open Remote Deskto Connection by going to Start -> Run (or press the windows key + R) and type “mstsc”
On the Remote Desktop Connection , at the top Right Click and slect About

Here we can see that in this example we are running version 6.2 and Remote Desktop Protocal 8 which is the correct version. Anything Previous to this will not function correctly
This New Version of RDP is automatically bundled with Windows 7 SP1 update so you can either ensure that your machine is up to date or you can manually install it by taking the following steps
1) To install the RDP 8.0 update, you must have hotfix 2574819 installed
2574819 An update is available that adds support for DTLS in Windows 7 SP1 and Windows Server 2008 R2 SP1 and can be downloaded from
http://support.microsoft.com/kb/2574819
2) Once the above is applied we can then install the new RDP Client update
http://support.microsoft.com/kb/2592687
It is important to do this install the updates in this order