I have seen issues like this at one of my old jobs using VDI. As a test have you tried to download and modify the .rdp file to include EnableCredSSPSupport:i:0 ? Please see the following article for more information: https://learn.microsoft.com/en-us/troubleshoot/windows-server/remote/remote-desktop-connection-6-prompts-credentials
RD Web gets stuck when there's an interactive logon message
Riley Weist
1
Reputation point
We've recently setup an interactive logon message via group policy, but it causes a login issue with RD Web.
When logging in to RD Web it'll get stuck on "establishing connection" and the show details button will light up.
If you click on show details it will show the interactive logon message and a user can then login, but it's not an obvious/user friendly solution.
Is there any way to mitigate this or have the prompt show up in the RD Web UI?