I don't know as much about this as others on the forum, but I think the point about the security of the wi-fi versus a wired modem has to do with access.. If you can access your modem, and therefore your network, by using Bluetooth technology, then could someone sit in your parking lot and hack into your system using their own computer and Bluetooth? What kind of encryption does this modem your are being supplied with offer? Does it have a built in firewall? (Is that still a thing?) If your network is only accessble though a wired connection, you would notice someone tapping into ii. That said, I trust my IT people, and we are running a wi-fi network that they assure me is secure and that allows my customers to sign in as guests.