List running VM:

VBoxManage list runningvms

Start the VM (for example VM:WinServer, type:headless):

VBoxManage startvm "WinServer" --type headless

Power Off the VM:

VBoxManage controlvm "WinServer" poweroff

Enable VRDE (VirtualBox Remote Display Extension):

VBoxManage modifyvm "WinServer" --vrde on

Check the RDP Port:

VBoxManage showvminfo "WinServer" | grep VRDE

Then use host IP to connect via RDP, this example is 192.168.1.10, while the VM on 192.168.1.11.

Connect to VRDE from Linux:

xfreerdp /v:192.168.1.10:3389

Connect to VRDE from Windows:

mstsc → 192.168.1.10:3389