Connected devices

I'm having issues with the xfinity app showing my connected devices using wifi, but some of them aren't even connected to the wifi. Examples: I just checked it and it shows my son's phone is connected to the internet, but my son isn't home. How can his phone be connected to the wifi if he's in a different city? Also last week it showed my Google home mini was connected and it was sitting on a shelf unplugged. Anyone else having these issues?