USB Tethering keeps disconnecting
USB Tethering keeps disconnecting
I'm trying to connect via USB tethering from my LG G4. I have Ubuntu 16.04
The tethering works for just 1 or 2 minutes but after that it disconnects. If I unplug and plug again the cable it reconnects, but just for another minute or so.
If I activate wifi tethering it works fine..
Can anyone give me some advice on how to diagnose and to understand why this is happening?
Thanks in advance :)
I've just experienced this exact same problem after upgrading to 16.04.1 from 14.04 (under which USB tethering worked fine for years).
Based on syslog it looks like it's caused by a conflict with ModemManager.
Aug 25 13:12:24 outback NetworkManager[2543]: <info> [1472145144.1334] device (enp0s20u2): Activation: successful, device activated.
[...eliding log entries related to nm-dispatcher services]
Aug 25 13:12:38 outback ModemManager[2503]: <info> Creating modem with plugin 'Generic' and '2' ports
Aug 25 13:12:38 outback ModemManager[2503]: <info> Modem for device at '/sys/devices/pci0000:00/0000:00:14.0/usb3/3-2' successfully created
Aug 25 13:12:41 outback ModemManager[2503]: <warn> couldn't load Manufacturer: 'Serial command timed out'
Aug 25 13:12:44 outback ModemManager[2503]: <warn> couldn't load Model: 'Serial command timed out'
Aug 25 13:12:47 outback ModemManager[2503]: <warn> couldn't load Revision: 'Serial command timed out'
Aug 25 13:12:50 outback ModemManager[2503]: <warn> couldn't load Equipment Identifier: 'Serial command timed out'
Aug 25 13:12:50 outback ModemManager[2503]: <warn> couldn't load Operator name: 'SIM failed to handle CRSM request (sw1 106 sw2 130)'
Aug 25 13:12:54 outback ModemManager[2503]: <warn> couldn't load IMEI: 'Serial command timed out'
Aug 25 13:12:54 outback ModemManager[2503]: <info> Modem: state changed (unknown -> disabled)
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.3879] device (enp0s20u2): state change: activated -> deactivating (reason 'connection-removed') [100 110 38]
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.3881] manager: NetworkManager state is now DISCONNECTING
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.4362] dns-mgr: Writing DNS information to /sbin/resolvconf
Aug 25 13:12:54 outback dnsmasq[4348]: setting upstream servers from DBus
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.4430] manager: (ttyACM0): new Broadband device (/org/freedesktop/NetworkManager/Devices/4)
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.4441] device (ttyACM0): state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.4445] device (ttyACM0): modem state 'enabling'
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.4457] device (enp0s20u2): state change: deactivating -> disconnected (reason 'connection-removed') [110 30 38]
I disabled ModemManager via the command:
sudo systemctl disable ModemManager.service
And then rebooted. My subsequent USB tethering sessions have been stable since then.
I'm sure there's a way to configure ModemManager properly for my phone (an LG G3), but I have no current need for a serial modem, so this method works for me.
If it is invalid, use the following command
$sudo systemctl stop ModemManager.service
https://askubuntu.com/questions/777945/usb-tethering-keeps-disconnecting
How to analyze that you cannot access the Internet after inserting the USB network card for two minutes (the network card has no IP address)?
1. Use dmesg to view the log information of the USB network card driver inserted
2.Check the syslog to see the log of the initial process of plugging and unplugging the usb network card and the log of NetworkManager abnormality.
Aug 25 13:12:54 outback NetworkManager[2543]: <info> [1472145174.4457] device (enp0s20u2): state change: deactivating -> disconnected (reason 'connection-removed') [110 30 38]