The issue might be caused by the wrong token being stored on the Windows Server 2019 machine. Please try the following: 1. Open the Windows Run dialog (Win+R) and type in regedit.exe to open the Windows registry editor. 2. Locate the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Usoris\Remote Utilities Host\Host\Parameters and delete it. 3. Reinstall the Host from the vanilla Host installer or your custom Host installer and see if the issue with the 2FA still persists.
In addition, in case if you use version 184.108.40.206 of Remote Utilities or any other older version, please try updating to the latest 220.127.116.11 Beta 2 version, as the issue might have already been resolved in the latest release. The latest 18.104.22.168 Beta 2 version is available for the download on this page. Please make sure to update both Viewer and Host to the same version as the version mismatch might lead to performance issues or some features not working.
Please let us know if this worked for you or if the issue persists.