Lost Connection to home internet network

my Mac won't connect to my home wi-fi anymore.I have changed no settings. I have 4 macs in my home. They all connected to the home wi-fi without an issue.Then one would not connect at all. Later a second one would connect to the xfinity general (unsecured) network then it stopped connecting at all, two others do not connect to home wifi any more but will connect to xfinity network. Have one older laptop (no connection at all), one older desktop (connects to xfinity),one brand new laptop (connects to xfinity) and one brand new deskto- (mac mini M4) that now will not connect at all. Old and new desktops are in same room!