No ethernet after RHEL8.2 to RHEL7.9

I had to load 7.9 on a Dell system preloaded with RHEL8.2.

The installation is now complete, but I have no ethernet connectivity any more. Of course things like the nvidia drivers are gone, but until I get connectivity I can't do anything about that.

I've seen online where there would supposedly be an ethernet slider on a screen that you move over and hey presto, but I don't seem to have any simple option like that.

How do I re-establish ethernet?

Thanks!