Don't think I can do an ethernet check because my ethernet connection on my iMac has been next to useless for years now and I have been using only the aiport card. I decided to instead compare my iMac to my son's iPad.

I took two readings for each a few minutes apart.

iMac 1st reading: ping 11ms download 15.11Mbps upload 1.90Mbps
iMac 2nd reading: ping 12 ms download 3.01Mbps upload 0.97Mbps

iPad 1st reading: ping 18 ms download 18.57Mbps upload 1.85Mbps
iPad 2nd reading: ping 20 ms download 14.58Mbps upload 1.95Mbps

The second Mac reading (which was very near in time to the 2nd iPad reading) seems pretty conclusive maybe?
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We are what we repeatedly do - Aristotle