I’m putting this out here just in case somebody else would be looking for it:

I put away my dear beloved an AMD 5800X3D CPU and my Nvidia RTX 3080 GPU because I’m taking a break from gaming. Instead, I installed a 5700G to conserve power. Upon booting for the first time, I had no internet connection. A quick glance at ip link and I noticed that the Ethernet interface no longer is called enp6s0 but enp5s0. Updating the interface name in my network config files solved the problem.

As a bonus, both the hardware and system clocks were also all over the place until I adjusted them…

I have no idea why a new CPU comes with these phenomena, but it did.