No one's gonna respond to your thread probably, I ran across it, so I will:
ISP supplied routers, especially WiFi ones, are woefully insecure and have shitty performance. The ISP has an incentive to make money, not give you the most expensive router on the market, just because you have service.
Most if not all consumer grade routers, especially in the $200-350 range have far superior performance to any ISP supplied router, not to mention you have control over that hardware and don't need to call them to ask for the admin password, or have to give it back when your subscription ends (like, if you move).
As for WiFi drops and issues, that's down to physics and electromagnetic properties. Slower waves penetrate mass better - faster waves have better speeds. 5.2 GHz and 6.0 GHz won't travel as far as 2.4 GHz. Do your research, but ideally, you want WiFi version 6 as a minimum for reliability, and 6 GHz if you're in a city or something.
Otherwise, go wired to the specific rooms if you're in a McMansion with lead-lined concrete walls and deploy APs as necessary on 5.2/6.0 GHz high-speed.
Wired > Wireless. Basically always.