Fixing the "Device Not Managed" Issue for the LAN Port on Ubuntu

Recently I noticed that after plugging the official LAN Adaptor into my laptop (a ThinkPad X1 Carbon 2017), the system didn’t show a new LAN connection. Instead it said “device not managed.”

Took me forever to find the fix.

sudo vim /etc/netplan/01-netcfg.yaml

In the original file

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s3:
      dhcp4: yes

change renderer: networkd to:

renderer: NetworkManager

then run

sudo netplan apply

and that’s it.

The reason seems to be that I installed this Ubuntu using the Ubuntu minimal method, and that network management mode is meant for Server, not Desktop, which caused the problem.

Source: https://forum.linuxconfig.org/t/wired-unmanaged-ubuntu-desktop-issue/1574/4