Thanks for the reply! Your note made me think about just checking the basics before any further investigating. So I quickly plugged my Ethernet cable into my Window 7 laptop (should have done that long ago!) to see if the problem occurred there as well. And it did!
So, I grabbed a new cable and hooked my laptop to the router with this new cable (desktop PC too far away to do the same with it) and lo and behold, immediate connection.
Made me think I may jst need a new Ethernet cable. But before spending the $ for 50ft of cable and then all the wire snaking involved, I wondered if it might just be possible that the plug at the router might be bad. I had been pretty rough in forcing that particular end of the cable up through my basement floor.
So I cut off about 1’ foot of wire and re-clamped a new plug on the end. Instant connection!
Hopefully that was all it was. Long way of saying thanks for getting my brain moving. Greatly appreciated.