Matte2--
What is the brand and model number of your router? Where is the router located?
Our router is on one side of the house and, like you, had significant dead spots on the other side of the house, I tried various routers but could never get decent connection in two of the rooms. I used Netgear range extenders, but even with the faster ones the wifi speed was pretty slow.
I came across an ASUS AC1900 router at a thrift store identical to one that I have, flashed both routers with Merlin firmware, and am using one as the wifi router and the other is configured to be a mesh router. Not sure about other manufacturers but ASUS has made it ricidulously easy to set up the second router as the mesh. So I think my set up is similar to Ruggy's.
The advantages of the mesh system is that there is a dedicated channel that the mesh extender communicates with the main router so you don't have a diminution in wifi speed compared to a traditional wireless extender, and you have the option of having the mesh have the same ssids and pws as the main router so the handoff between router and mesh is seamless.
Am sure that other manufacturers have mesh extenders (I know that Netgear does for sure) that work with their products, so I don't think you need to go out and buy a complete mesh system (they can be pretty pricey, but from an esthetic stand point, some of the mesh systems look less obtrusive than the standard routers and extenders--thankfully the mesh extender is in my office so the spouse doesn't care how it looks).
We now have great wifi coverage throughout the house (and even in the garage) and the audio and video on our doorbell camera is smooth without any choppiness.
Also, with the mesh system there are just 3 wireless networks in our house--2.4g, 5g and guest, with the extenders we had 6!