That turns it into a WIFI presence sensor 
See Presence sensor... device associated with local wifi and several other posts on “Wifi presence sensor”
FYI, yes, my own homespun version of this (looking for devices ON the local wifi network) works great, and since it’s not on the phone itself doesn’t require any mojo on the phone - works for android, ios, whatever you have that associates to your local wifi when you are home…