This seems to be a longstanding bug that has appeared in many releases.
A fresh install of Ubuntu Desktop 20.10 does not show the Wired Network Settings.
I only have Wireless internet access. Turning this off results in no internet.
The ethernet cable is working, since Windows on the same PC running on it. The ethernet LED lights are also indicating a connection and on Manjaro - which I had installed previously - had an ethernet connection.
Therefore I suspect the problem to reside in Ubuntu software.

No wired network settings:

Running the following line results in the following output:

sudo lshw -c net

Output:

Does anyone know how to let the wired network setting appear, and enable ethernet?