What would be roughly the lower end of an acceptable wifi signal strength?
My brother isn't satisfied with his router's signal range, and asked me to help improve it. I was thinking maybe have the router on one side of the house and a repeater on the other side, and for them to be connected with a power line adapter if the wiring permits, or Ethernet cable if not. That way the router and repeater will have distance to reduce some of the interference created by overlapping signals, and the signal range would be as wide as I can get it. But for all I know, there might still be spots that are too weak, and require another repeater. Or maybe I just need to put an app on their phones to connect better to a weak signal. I don't know yet.
But before I buy anything or decide for sure what I'm going to do, I want to get an idea of where the weak spots and dead spots are, including the driveway (he wants to connect while in his driveway sometimes). So I put an app on my phone that measures the wifi signal in dBm. I want to try to make it so him and his family can usually get an acceptable connection in any of the places in their home that they are likely to be while using the internet. But some devices are able to connect to a wifi signal that is too weak for another device. So I need to have an idea of what the bottom end of acceptable would be. By acceptable, I mean a signal strength that is enough to let all properly working devices maintain a connection most of the time that is good enough to browse web pages and watch youtube.
Your opinions would be appreciated.