Unlike rsync, or KDE Connect, there is no option to automatically allow the Calibre ebook manager to open ports so external devices can connect to it. So far, my solution has been to disable the firewall before connecting my device to Calibre via the Calibre Companion app on Android. For those unfamiliar with the process, Calibre Companion can sync ebooks from the desktop's library to the Android device's library, thus eliminating the need for wires and further organization of books. If I know I am using port 9090 for Calibre, is there a way to allow this connection in the Firewall? Has anyone else attempted this setup? Running netstat shows this additional parameter enabled when my tablet is connected to the computer. tcp 0 0 10.42.0.1%2457529:39858 10.42.0.250%328:sesi-lm ESTABLISHED