X11vnc (from Arch Wiki). I upgraded my basement NAS to the newest Ubuntu Server and now running a Virtualbox VM as a user doesn't work for RDP (for some reason it will not grab the right port). Since the VM is another Linux system I ended up setting up x11vnc on it so at least I still have remote access. I don't even know how to troubleshoot the Virtualbox issue so I guess this is how it works now.