It seems that both ModemManager and NetworkManager are doing the right thing
Apr 27 10:57:05 Paul-HP-Laptop ModemManager[846]: <info> Modem /org/freedesktop/ModemManager1/Modem/1: state changed (enabling -> registered) Apr 27 10:57:06 Paul-HP-Laptop NetworkManager[898]: <info> [1493254626.0016] (ttyUSB2): modem state changed, 'enabling' --> 'registered' (reason: user-requested) If you're able to reproduce the issue, could you please enable debug logs in both NetworkManager and ModemManager? Please do the following (I know, it's a bit long, sorry for that) $ sudo systemctl stop NetworkManager $ sudo systemctl stop ModemManager $ sudo NetworkManager --log-level=DEBUG --debug | tee $HOME/network- manager.logs then open a new shell and run: $ sudo ModemManager -d | tee $HOME/modem-manager.logs and then attach the two log file in your home directory -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to plasma-nm in Ubuntu. https://bugs.launchpad.net/bugs/1686573 Title: USB Modem not displayed in network manager To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/modemmanager/+bug/1686573/+subscriptions -- kubuntu-bugs mailing list kubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs