Users get randomly kicked out of RDS sessions on 2016 RDS server

restart manager has to do with restarting the pc for windows updates (usually)
https://docs.microsoft.com/en-ca/windows/desktop/RstMgr/about-restart-manager

Are the users local to the Remote Desktop Session Host(s) or remote?

If they are remote, verify their internet connection isn't being saturated and thus causing network drops.

Are the user's sessions being outright killed as in when they go to log back in they get a fresh session with their work lost?

Thank you for your reply both of you.

The users are local. As to your other question I will check it out and get back yo you.

I am aware that Restart Manager normally logs restarts. But there is no way the server restarts that many times during work hours. That I would have noticed.

Are the users getting disconnected or logged off? Do they have Admin access on the server?

The users get disconnected. When they reconnect their old session is still active. The users do not have any administrative rights on the server.

Check if server has Group Policy enabled for Sessions disconnection after a period of time.

Computer Configuration\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Session Time limits.

Thanks for the tip, but that is not the cause of the problem. Actually, a colleague of mine found the solution. It was GPO trying to install a printer driver during user logon to the RD server. The installation failed and then Windows Installer started to clean up after the failed installation. It was Windows Installer that triggered Restart Manager as a part of the cleanup, and one of the things Restart Manager did was to reset the user connection to the RD server. So, Restart Manager obviously does more than restart the server. A strange thing is that Restart Manager logs even more events now than before we stopped the failing GPO, but that is a different matter. Thanks to everyone for contributing.

Regards
Pål Berg

Thanks to everybody who participated. I know have learned  that the Restart Manager obviously does a lot more than restart computers after running Windows Update.