HP lt4120 failing to make single-stack connections on LTE using MM

[Tore Anderson]

* Aleksander Morgado
>>
>>>     $ sudo mmcli -m 0 --reset
>>
>> Thanks - I had overlooked that one, but it doesn't quite work:
>>
>> error: couldn't reset the modem: 'GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Unsupported: Cannot reset the modem: operation not supported'
>>
> 
> Oh wow, which MM are you using? This has been implemented for QMI
> modems since a very long time ago.

Whatever's in Fedora - v1.6.12. Guess I should upgrade. :-)

> The correct sequence is: --dms-set-operating-mode=offline and
> --dms-set-operating-mode=reset :) That is what MM does when you run
> "mmcli -m 0 --reset"

That kicked it off into some sort of endless reboot sequence.
Cool! :-)

A full power cycle of the laptop didn't even fix it. I actully needed
to boot the laptop into Windows 10 to make it work again...wonder why.

I'll dig some more. Might be that the mmcli --reset actually is a
dangerous command on this particular modem.

Tore