How to understand macOS wireless diagnostics?
I advise you to use this diagnostic tool twice:


in the exact position where you intend to place your Wi-Fi router,
in the exact position where you want to get the best access for your Wi-Fi client.


The number inside brackets are channels to avoid, the others the ones to use.

From your diagnostic results it would be a bad idea to use the “automatic” channel selection on your router because this is conceptually a total error as soon as you have neighbours networks. The router cannot diagnose the wireless environment where you will seat with your iPhone.

From the partial results you got, I advise you to configure your router to work on channel 36 (5 GHz) which won’t be subject to interferences (as it will be the case with channels 1, 4 and 11 even if they are actually free.

If you want to further improve your skill in the wireless world, I suggest you to try iStumbler. It is now a commercial product but it worths much more. I use it since many years in private and professionnal environments