There is a known error with RDP on windows 10 and VirtualBox
https://www.virtualbox.org/ticket/14216
I'm running openmedivault-virtualbox 1.3 and can no longer access any of my VMs through RDP as I've gone and upgraded to win 10 on my client PCs.
In the thread linked it suggests that the extension pack for virtualBox fixes the problem, but I've downloaded and (re)installed the pack and the problem persists.
Any chance there will be an update to this Plugin, anyone else come across this.
P.S. sorry if there has already been a thread on this...