i downgraded ModemManager back to 1.6.8-2ubuntu1 and the problem went away, so it is caused by ModemManager.
attached are the logs for ModemManager 1.6.8-2ubuntu1 ** Attachment added: "mm.log" https://bugs.launchpad.net/ubuntu/+source/modemmanager/+bug/1819615/+attachment/5260385/+files/mm.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1819615 Title: For additional hardware support, modemmanager needs to be upgraded to 1.10 on Bionic To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/1819615/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
