not overly surprised that changing the boot-up order, so that the new router (on its new ethernet cable rather than my previously installed one), was the first thing my old computer saw when powered up, made not the slightest bit of difference to the new router's refusal to talk to my old computer.

WOC tech bod had had the clutching-at-straws notion that the cable might matter (despite admitting my existing cable was good enough and their network card should also have been good enough). So I needed to test both things.

very relieved that my old computer was able to get back to using the old router - significantly without requiring any reboot or other changes - and that I hadn't broken anything (including myself!) noticeably in the process.

some time off from fighting with the hardware now. It was incredibly difficult to get my original cable out of the socket at all - not just because of the unfavourable location & angle but because its locking tab is too close to being inside the backplate for good depression & withdrawal.

for a very long time of repeatedly trying with alternate grips that it might somehow have become welded in there - and that I'd break it completely while making the attempt to remove it.

Can you test the new router on another comp?

it to work on an old computer. The tests with the laptop (which is largely useless for anything important) have already been done.