If SIM in a modem is locked, ModemManager can't initialize SupportedIpFamilies
and NetworkManager will set the property to 0. ModemManager then updates the
property after the modem is unlocked, but NetworkManager did not watch changes
to the property. And that resulted in a connection failure:
(ttyUSB1): Failed to connect 'O2 Internet': Connection requested IPv4 but IPv4 is unsuported by the modem.
(ttyUSB1): device state change: prepare -> failed (reason 'modem-init-failed') [40 120 28]

https://bugzilla.redhat.com/show_bug.cgi?id=1263959