A few days ago, Ubuntu told me it could be upgraded to 22.04, the new LTS version called Jammy Jellyfish. I thought it was the right moment, so I went ahead. I have to say that I faced several issues, such as some problems with Python3.10 that affected many applications (you know, Ubuntu uses Python a lot), but they were easy to solve with a few reinstalls. However, I was really upset when I saw that my Ethernet interface was not working.

The Ubuntu settings did not even detect the wired connection, but the interface was there:

$ sudo lshw -C network
  *-network DISABLED
       description: Ethernet interface
       ....
       logical name: enxe4b98
       ...

So Ubuntu had to bring up the interface at boot time and configure it using DHCP.

/etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

+# workaround for ethernet
+auto enxe4b98
+iface enxe4b98 inet dhcp

Then restart NetworkManager:

$ sudo systemctl restart NetworkManager

The interface was now detected by the Ubuntu settings, but it was unmanaged:

$ nmcli device
DEVICE           TYPE      STATE        CONNECTION 
enxe4b98         ethernet  unmanaged    --

We can apply a workaround to NetworkManager to make it work:

/etc/NetworkManager/conf.d/allow-unmanaged-devices.conf

[keyfile]
unmanaged-devices=*,except:type:wifi,except:type:gsm,except:type:cdma,except:type:ethernet

And restart NetworkManager again:

$ sudo systemctl restart NetworkManager

Now your Ubuntu machine will be connected to the Internet over Ethernet.

$ nmcli device
DEVICE           TYPE      STATE        CONNECTION 
enxe4b98         ethernet  connected    enxe4b98