I have a Chromebook in my office, connected to the router via; an ethernet cable, into a 4 way switch, out of the switch then into the powerline adaptor, out of the powerline adaptor in the router closet, and into the back of the router.
Speedtest in that config - ~50Mps.
Shunted the powerline adaptor with a long cable from the switch _ 100 Mps. Shunted everything with that LONG ASS cable directly from the Chromebook into the router - 200 Mps, just like Cox promised !!!!
BTW 50 Mps is plenty to do anything, including multiple 4k video streams. How fun!
P.S. "Shunted" = went around