RDP connects once, but not again unless reboot

Preface: I’m running into this issue with increasing frequency. It seems related to Windows 10 2004 and/or 20H2 - prior to these versions everything was fine. All RDP sessions are being accessed over OpenVPN. The VPN connection seems to be working fine.

Issue: I have multiple clients who can RDP into their workstation once and it works fine. Once they disconnect, they can’t connect again unless the machine they’re connecting to is rebooted. A different client can connect without issue, once, but not again - same story. I can’t find any firewall blocking going on on either their main firewall or the Windows firewall. It’s like the service just stops responding to requests from any clients who have connected before until the reboot and then it starts all over again.

Anybody have any ideas?

Install a VNC server on one of the workstations and try to connect with VNC after the RDP fails. This will let you know if the RDP is being blocked on the second attempts.

Are the workstations missing any updates?

And all that said, RDP has gone through some changes lately to plug some security holes, I’m wondering if the second attempt is blocking the connection based on a security issue. Big guesses but how I would go about this to figure out what might be happening.

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Greg, sorry, for some reason I didn’t notice a reply had been posted. I’m pretty sure this is related to Windows updates having not been applied, but as this occurred with two different clients and I’ve only been able to get one of them to follow through with doing anything. The updates on the one machine did seem to resolve the issue. She was on v1909 and the machine she’s was RDPing into was on v2004. Once she updated hers to 20H2 it seemed to work.

Oh, yes there was a January and February update that fixed some security issues with RDP.

Good to know, thanks. Between Windows and Microsoft 365, Microsoft releases so many updates it’s impossible to keep up with release notes. I’m going to have to venture into uncomfortable territory and force clients to either get on maintenance plans or deal with increased hourly rates.