My wired connection does not work. What information is needed to diagnose the issue?

Question

I wish to build a question that would fix the information gathering problem for wired issues. This is just like my-wireless-wifi-connection-does-not-work-what-information-is-needed-to-diagnos. Hopefully one can then build up a script that eases the headaches for wired connections too.

This would make the following questions more systematic

• Wired connection unmanaged - ubuntu 18.04 (common solution does not work)
• Ubuntu 18.04 Ethernet not managed
• Ethernet device not managed
• Ethernet Network() device not managed ubuntu 16.04

Answer 1

Currently, these are the ones that I can think about.

• sudo lshw -C network
• ip link show
• ip addr show