Remote Desktop Gateway fails with mstsc from Windows 10, works with xfreerdp from Ubuntu

Question

Setup:

• Remote Desktop Gateway - Server 2019, local user group on the gateway server that is allowed to use the gateway, list of computers that are available through the gateway
• Remote Desktop Session Hosts - Server 2016
• Clients: Dualboot Windows 10 LTSC (1809) / Ubuntu 20.04 LTS

Situation:
Trying to connect through the gateway from a Windows Client fails with "The Remote Desktop Gateway is temporarily not available" after several minutes
Using Ubuntu on that same computer the connection works almost instantly.

What i tried so far:
Registry keys:

• RDGClientTransport set to 0 or 1 - does not work
• LogonTimeout on the server set to a larger number, did not work

I am stumped. Connection works flawlessly from Linux using xfreerdp but does not work with mstsc.

Any suggestions?

Answer 1

Further investigation with the Windows client:

• Querying the IIS default page of the Remote Desktop Gateway Server works fine
• netstat shows an established HTTPS connection from the client to port 443 on the Remote Desktop Gateway when a connection attempt is made
• Replacing the FQDN of the Remote Desktop Gateway with its IP-Adress in mstsc.exe results in a "certificate and host name do not match" error when trying to connect

Out of ideas.

Answer 2

Hello @Andre Weidner

I would suggest to check below.

1. Please try yo make your Ubuntu machines and Windows 10 machines are on same network ip ranges.
2. Have you published ssl certificate to RD Gateway role.

Please have a look in below Microsoft thread for similar issue which may help you.

https://social.technet.microsoft.com/Forums/en-US/a87e8036-ddce-403e-9243-d29fdfbe627e/the-remote-desktop-gateway-server-is-temporarily-unavailable?forum=winserverTS

If the reply was helpful, please don’t forget to upvote or accept as answer.

Answer 3

1. It is the same computer. I just reboot from Ubuntu to Windows. Same IP-Address, same network, same cable, same switch ...
2. Yes, i did.

The Remote Desktop Gateway is reachable from the internet and the LAN with the same FQDN. If i use Ubuntu and freerdp, it works from the internet and the LAN. If i use mstsc.exe it does not work.