They won't show up on your local network. They're on a type of guest wifi. If you connect to your local Xfinity wifi connection, you might be able to sniff the

They won't show up on your local network. They're on a type of guest wifi. If you connect to your local Xfinity wifi connection, you might be able to sniff them out, if the wifi allows "promiscuous" connections. (Promiscuous mode works because LANs are like cell networks - they operate on an "honor system", where all devices on the network receive all IP packets, but ignore those which don't match their address.)