people use crap routers from their providers instead of buying one that has two way or dual bands for wifi. Usually the $150 model..
I recently looked at changing from Comcast to ATT for their hyped gig speed. They have a low buy-in price for 1 year then it jumps up.
I could deal with that but they REQUIRED that I RENT their equipment.
No deal.
Years ago I had ATT DSL with their crap Motorola modem. After so many problems I scrapped it, bought a Linksys and had no more problems.
With Comcast cable I use a Netgear Nighthawk plus Google Nest wifi. No down time. No dead spots.