Originally Posted by JimE
If everything is working, just leave it alone.
I completely agree with Jim. If you are not having any real issues in your home with all of your WiFi devices then simply ignore the marketing campaign targeting your specific wallet.
The only reason why I own my own router and my own modem is to save myself money from "rental fees." The initial down payment to buy your own router and modem combination can cost anywhere from 180 dollars to 500 is all down to what your specific needs would be.
Questions to ask yourself: Are you playing video games on your wifi devices? Are they action based twitch gameplay that requires your every input to gain an advantage? Then yes. Purchasing your own internet modem and router would be the way to go as rental modem router combo's are never good enough. But if you are not playing games like counter strike, rainbow six, PUBG, Fortnite and so on (or anything on console or PC. Console being a nintendo switch, a playstation 4, xbox, Wii, ouya, stadia.) then what you have is already the best that WiFi can offer.
If you are watching Netflix, Hulu, youtube, or any video service on a regular old 1080 P TV? then you already have the best WiFi setup. If you have a brand new 4K TV? Then you might want to buy that wifi router modem combo. But chances are the router modem combo you already own can already handle 4K movies and video. (4K resolution is above 1080P to tell the difference between 1080P and 4K would require you to own a movie theater sized screen. a 50 footer. not incher.) So unless you own your very own personal 50 foot movie theater screen then you really don't need 4K resolution. The only thing that you would be able to tell the difference on is frame rate.
If you are using the WiFi on your phone, tablet, PS Vita, Nintendo 3DS, or any handheld gaming device that is not the Nintendo switch, then you already have the best that WiFi can offer to those devices.
If you have Alexa, google, or the apple Siri voice command in your home? Any wifi signal works best for those devices already as the amount of information those need to run can be done with a 56K modem (Dial up internet speeds at 56K. Think America Online when it first came out.)
So what ever marketing campaign is currently being flashed before your eyes causing a doubt in your own setup is nothing more than a campaign to get you to spend that money.