After working successfully for a few minutes (using automatic port mapping with UPnP), I try to run the connection test in Screens Connect again, and it returns the error "Port Mapping Unavailable. Check your router settings." UPnP is definitely turned on, and Screens Connect supports it. I've tried using port forwarding as well, but I've never been able to get it to work at all. Port forwarding works fine for remotely accessing my Plex and Calibre libraries, but for some reason will not work with Screens Connect.