It's insinuating the WiFi network he joined is actually someone's hotspots, pretending to be public WiFi - for the purpose of hacking anyones device who joins. The 172.16 IP address is not normally used on most (public) WiFi networks - therefore suspicious 

 Thanks. 

 Thanks very much for this info 🫂 

 Thanks for this explanation! 

 Thanks for asking to explain. I was clueless also. 

 always learning 

 Absolutely. The only way to go.