[Fuexline]

in nem englischen Forum war das die Lösung:

I went into the Remote tab of computer properties - turned off allow RDC and then turned it back on. That's it. It's working now. Don't know why I didn't try that before. I've been messing around with this for a week or so on and off when I had time.

I found that somehow, the current network got switched to Public Network instead of Private Network. RDP is automatically set to deny connections when it's set to a Public Network. I switched my network type to Private and it fixed everything.

EDIT: You can test this by going into the Windows Firewall settings > Inbound > Remote Desktop - User Mode (TCP-In) > Advanced Tab > Check the Public box, then try and RDP into the server.

A GUI way of making this change:

Hit Winkey R to open Run prompt and type gpedit.mscNavigate to: Computer Configuration/Windows Settings/Security Setting /Network List Manager Policies.Choose your Network name in the right panel.
Note: To show networks not currently connected, right-click Network List Manager Policies in the left pane and choose Show All Networks.
Go to Network Location tab and change the Location type from Public to Private.

das mal testen