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stiv
Asked: 2019-12-05 07:14:24 +0800 CST

Wired network interface randomly goes up

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I am using desktop Ubuntu 18.04.3 LTS, I have to wired network cable connected, I am working over WIFI. But sometimes, when I work, suddenly I get annoying notification that enp108s0 interface is up in my tray (I haven't connected my cable). If I disconnect it, it goes up again later. How can I fix it?

UPDATE: sudo journalctl /usr/sbin/NetworkManager gives the following:

дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0478] keyfile: add connection in-memory (b71c8ace-4a82-4c78-8d77-251ed1830d18,
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0489] device (enp108s0): state change: unavailable -> disconnected (reason 'co
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0509] device (enp108s0): Activation: starting connection 'enp108s0' (b71c8ace-
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0621] device (enp108s0): state change: disconnected -> prepare (reason 'none',
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0633] device (enp108s0): state change: prepare -> config (reason 'none', sys-i
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0637] device (enp108s0): state change: config -> ip-config (reason 'none', sys
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0638] device (enp108s0): state change: ip-config -> ip-check (reason 'none', s
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0645] device (enp108s0): state change: ip-check -> secondaries (reason 'none',
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0649] device (enp108s0): state change: secondaries -> activated (reason 'none'
дек 04 21:59:02 freetrade NetworkManager[988]: <info>  [1575471542.0675] device (enp108s0): Activation: successful, device activated.
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0002] keyfile: add connection in-memory (644e81fb-fee0-41d4-abec-bf2ca40d4ada,
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0030] device (enp0s31f6): state change: unavailable -> disconnected (reason 'c
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0161] device (enp0s31f6): Activation: starting connection 'enp0s31f6' (644e81f
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0661] device (enp0s31f6): state change: disconnected -> prepare (reason 'none'
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0672] device (enp0s31f6): state change: prepare -> config (reason 'none', sys-
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0676] device (enp0s31f6): state change: config -> ip-config (reason 'none', sy
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0678] device (enp0s31f6): state change: ip-config -> ip-check (reason 'none', 
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0686] device (enp0s31f6): state change: ip-check -> secondaries (reason 'none'
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0690] device (enp0s31f6): state change: secondaries -> activated (reason 'none
дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0760] device (enp0s31f6): Activation: successful, device activated.
networking 18.04

2 Answers

  1. The log entry

    дек 04 21:59:12 freetrade NetworkManager[988]: <info>  [1575471552.0030] device (enp0s31f6): state change: unavailable -> disconnected (reason 'c

    although incomplete, and considering there are no preceeding warnings, implies (to me) that you have a physically intermittent connection.

    Wiggle your network cables, and if anything moves or the network bounces, replace it.

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  2. Get a flashlight, and check the pins in the wired Ethernet socket.

    enter image description here

    A foreign object pushed in there can case them to short, which will result in the intermittent symptoms you experience.

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