I've created a windows 10 Pro virtual machine (21H1) in virtualbox 6.1.26 on a Linux Mint host.
The network adapter is bridged and the VM is pingable on the local network at its IP Address.
I've set VirtualBox's display setting for the VM to enable the server on port 3389 with null authentication.
I've been through the Windows settings to ensure that Remote desktop is enabled and
netstat -an | find "3389" shows that the VM is listening on port 3389 for both TCP and UDP protocols.
When I try to connect from another machine on the network (I've tried with a Windows 10 machine as well as trying to RDP from the Mint Host box into the VM using its IP address) I am prompted for the username and password, but on providing these the connection appears to begin (the VM in the background locks the screen) but then immediately disappears and the rdp session never begins.
I've checked the event viewer on the VM for the remote desktop connections but it shows an event id 1149 which seems to indicate that the authentication was successful as it notes the username and the correct incoming IP address for the Host machine - there's nothing indicating why the session immediately drops.
Have I missed something in the configuration of either VirtualBox or the Win10 VM? Any suggestions appreciated.