Shout out to Greg!
After switching from a modem AND a router on my 2nd floor to one piece that's both-in-one AND buying the exact (WiFi-boosting) item that he recommended to me (Hell...my man even saved me a fiver - by suggesting that I print out the page that he'd linked me to (which had said item advertised for $5 less than the store shelf did))...
...I now have wired PS3 & PS4 connections that are consistently working!
Thanks with a smile, brother Argyle
Look at me throwing arounds words like "modem" & "router" as if I had a clue about what they do/how they work