This is not a NetworkManager problem. It is also reported by me in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1950385 and it is probably kernel bug. The problem is described by ModemManager's developer in our discussion: https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/463#note_1157289 as a broken USB communication. According to diagnosis from kernel 5.1x the qmi_wwan module resets modem firmware in endless loop: https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/463#note_1157919 although it was worked flawlessly earlier in kernel 5.8.x
The workaround is to use udev script for a modem to switch it to the MBIM mode which works ok under ModemManager & NetworkManager. Tested on kernels 5.8, 5,11, 5.13. Place the attached config file in: /etc/udev/rules.d instead of any old one. It uses usb_modeswitch to do the "magic" correctly. ** Bug watch added: gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues #463 https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/463 ** Attachment added: "Udev script for switching modem" https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1574582/+attachment/5541060/+files/99-hp-lt4120.rules -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to network-manager in Ubuntu. https://bugs.launchpad.net/bugs/1574582 Title: HP lt4120 Snapdragon X5 LTE USB modem not recognized by network- manager Status in network-manager package in Ubuntu: Confirmed Bug description: USB modem not recognized by network-manager. Modem information in attached ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: network-manager 1.1.93-0ubuntu4 ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6 Uname: Linux 4.4.0-21-generic x86_64 ApportVersion: 2.20.1-0ubuntu2 Architecture: amd64 CasperVersion: 1.376 Date: Mon Apr 25 11:14:04 2016 IfupdownConfig: # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback IpRoute: default via 10.106.36.1 dev wlp2s0 proto static metric 600 1.1.1.1 via 10.106.36.1 dev wlp2s0 proto dhcp metric 600 10.106.36.0/22 dev wlp2s0 proto kernel scope link src 10.106.39.123 metric 600 169.254.0.0/16 dev wlp2s0 scope link metric 1000 LiveMediaBuild: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1) NetworkManager.state: [main] NetworkingEnabled=true WirelessEnabled=true WWANEnabled=true ProcEnviron: TERM=xterm-256color PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: network-manager UpgradeStatus: No upgrade log present (probably fresh install) nmcli-dev: DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH wlp2s0 wifi connected /org/freedesktop/NetworkManager/Devices/1 IQORAMS_REPAIR 3b1e13ff-f9c9-4a49-a576-465bc2713e21 /org/freedesktop/NetworkManager/ActiveConnection/1 enxb2e41f35ffe1 ethernet disconnected /org/freedesktop/NetworkManager/Devices/2 -- -- -- enp0s31f6 ethernet unavailable /org/freedesktop/NetworkManager/Devices/3 -- -- -- lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/0 -- -- -- nmcli-nm: Error: command ['nmcli', '-f', 'all', 'nm'] failed with exit code 2: Error: Object 'nm' is unknown, try 'nmcli help'. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1574582/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
