Network Security

Good chance the question does not technically belong here but I have to give it a shot incase someone has any knowledge about this. Three other vendors have provided no answers. (AT&T, Brinks & Alarm dot com) I had been having issues with a wifi-extender dropping internet but I am determined to fix this. So I unplugged all routers, extenders/repeaters, all wireless devices except three due to reachability. Namely my 3 outside Brinks/Alarm.com wireless cameras. Okay, I plugged back in my Pace5268ac router with wifi disabled and using ethernet to a laptop. For whatever reason I had decided go to alarm site and check to see the outside cameras. Stunned. One of them was providing a live picture. How? The camera itself does not provide its own internet. (I didn't plug back in the inside cameras, gulp) I can only surmise that it somehow connected to a neighbor who had for the moment a unsecured router with the same SSID (??). So that begs the question: are devices always going to choose the router with a password or can an unsecured same SSID win out? Is there a Norton product for this? There is one more caveat and that no one and I mean no one, can answer what exactly the "private lan" setting for the guest network on the Pace5268ac router does or means. Is it, when enabled, access to the home network or is it creating its own private network as oppose to a public and maybe passwordless network. I have notice a few ATT routers in the neighborhood. Thoughts?

well…so much for that

One more piece, I now have changed these cameras connecting to a TPLink ax21 using WPA3 via the Pace5268ac.