Mobiles connecting to WiFi

Hi there, just downloaded Glasswire to understand my WIFI bandwidth usage and discovered I have figures 2 android mobile phones connected TO MY WIFI !

Can I block their connection and if so how please I am truly horrified! The software shows their IP address and a another number [is it a MAC no?]

kind regards


if you have unauthorised devices on your network, change your wifi password in your router/access point