I was having issues getting a decent wifi signal from my Netgear Nighthawk router outside in the front yard as well as the backyard. The Comcast tech support agent who came out to the house to replace the modem said I should look into "satellite mesh networks" for residential use. I asked him if this was a "range extender" and that I had tried those and didn't have good results. He said "No, these are better!".
After asking on r/HomeNetworking and looking on Amazon for some Netgear satellite mesh network setups I decided to try the "NETGEAR Orbi Wall-Plug Whole Home Mesh WiFi System - WiFi Router and 2 Wall-Plug Satellite Extenders with speeds up to 2.2 Gbps Over 5,000 sq. feet, AC2200 (RBK33)" solution from Amazon.
Its a bit more expensive at $255 USD, but I read good things about them and some people on Reddit said they work well.
The basic setup for Comcast (cable) is external modem (Netgear/sold separately), 1 wifi router (Orbi router) and 2x satellites (Orbi satellites, sold together).
After trying with the Comcast modem which didn't work I had to re-install my old external modem that I was using up until the support agent came to my house to replace it with an official rented modem. I then had to call up Comcast's automated support number which I found from gethuman.com and activate the new modem. Once I did that the Orbi router recognized the Internet connection and I was on my way.
One annoying thing is the instructions told me to install the Netgear Orbi app on my smart phone, which I did, but I had to create an account and save that in LastPass which is a bit of a pain in the ass on a phone. However I later realized I could access the router directly by browsing to http://192.168.1.1 and enter the username and password from the router sticker.
Once I performed all the firmware updates and configured my SSI network name and password, I also enabled the guest wifi network as well.
I placed the two satellites on either end of the house as the Orbi router is in the center of the house in the office. This was easy, you just plug them into the wall, but they take up space so I had to buy some power strip extenders to make room for the other things that were using the outlet.
It's been about 24 hours now and I am getting full bars on my laptop and phone from the backyard and the frontyard now, where as before I had to restrict my usage to 4Ghz network and I only got 2 bars with sporadic connectivity.