How to test speeds and strengths of wifi from macOS?
The WiFi Explorer tool will show you all the wifi connections your computer is capable of seeing. I live in a high rise apartment building and I receive signals from about 50 other modems. WiFi explorer will plot the signal strength of all these or the SNR of these signals. It also gives the channel number of each one. Its an excellent diagnostic tool for WiFi.
The basic package is $20 but there is a lite version that is free. I'm not familar with the lite version so I don't know what it does. Since it's free it is probably worth a test drive. The basic version has a 3 day free trial. There is also a Pro Version for $100. It has a 7 day trial.