Most of my electronics are at probably a decade or so old.
But I’m paying for 50 Mbps and my laptop is situated at
about the half-power point away from the router.
Verizon FiOS in the neighborhood is a lot higher than 50 Mbps
for those willing to pay.
Your hypothesis fits the possibilities.
I did replace the wifi unit in the laptop with a $20 unit
from Dell once, hoping for better performance, but there
was no change in performance.
64-bit MX-18.2 using 4.20.12 Kernel LiveUSB on Dell Laptop