I live in a senior community that has its own Wi-Fi. But I pay for a faster Wi-Fi from the cable company which is connected through a NetGear wireless router about 5' and a wall behind me. My wife's computer is in the same room as the router. Quite often, when the computer wants to do something connected, I get a pop-up menu which people who connect to the community Wi-Fi get every couple of months. So I click on the Wi-Fi icon at the top of my Mac, and see the visible networks, with my home network missing. I wait 10 seconds or so, and my home network shows up, and I connect to it. Comparing my wife's network preferences with mine, I see my family network listed first - and then on my computer lots of other networks - apparently those that I have connected my phone or my pad to away from home. My wife doesn't do that with her phone. (We share the same iCloud account). I do have an unused and unconnected Airport Express, but suspect that won't help.