Disconnect with non LTE capable provider

[Guido Günther]

Hi,
the umts modem in my laptop (Huawei ME906E) is LTE capable while my
provider isn't. Whenever the modem sees LTE it tries to upgrade the
connection and then disconnects:

ModemManager[3010]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed (home -> idle)
ModemManager[3010]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: 3GPP location updated (MCC: '0', MNC: '0', Location area code: '0', Cell ID: '0')
ModemManager[3010]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: access technology changed (umts -> lte)
ModemManager[3010]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: signal quality updated (26)
ModemManager[3010]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connected -> disconnecting)

This is ModemManger 1.2 and connected via

    mmcli -v -m 0 --simple-connect="apn=internet"

(but it's the same using NM). I wonder how to disable LTE for these
situations and how to expose this in a user friendly way in NM since
this might be a rather common problem.
Cheers,
 -- Guido