I recently upgraded my home network.
My wife wanted all equipment hidden, so I had the modem/router installed in my media closet in the basement. The signal was fine in the front half of the house, both downstairs and upstairs, but in the guest bedroom and master bedroom, it was virtually unusable. I tried a signal extender, and while that made it better, the service was still slow, and I usually had to manually switch to the correct network when I moved around the house.
A number of companies have popped up recently with easy to use mesh networks. Google just unveiled there version a couple of weeks ago. I went with the eero wifi system with 2 routers. The difference was night and day. Basement speed went from 45mbps to 85mpbs and the master bedroom went from 5mbps to 60mbps. Best part is that it took maybe 5 mins to setup. There are cheaper ways to achieve the same results, but none as as easy as this. There are other options as well.
https://eero.com/