Sierra Wireless EM7455

Ralph Plawetzki ralph at
Wed Jun 1 08:49:35 UTC 2016

Am 01.06.2016 um 10:31 schrieb Bjørn Mork:
> That's unexpected. This isn't going to be easy :(

Thanks anyway!!

> Wild guessing now. Maybe the network/modem/MM don't like that you didn't
> disconnect first?  You could try a full reset, followed by the same USB
> reset and *then* fcc-auth + connect.  But I don't know what you have to
> do to achieve a full modem reset.  Maybe "mmcli -m X -r" (replacing X
> with the modem index) will do?  Or maybe you can do it with rfkill?  Or
> maybe you have to reboot the laptop?
> In any case, the theory is:
>  1. Get the modem into a clean initial state
>  2. USB reset
>  3. FCC auth
>  4. connect

Yeah I thought about this direction too and tried it before.
Unfortunately resettig the modem seems not that easy:

[rallo at six ~]$ sudo mmcli -m 0 -r
[sudo] Passwort für rallo:
error: couldn't reset the modem:
Cannot reset the modem: operation not supported

Sierra does not offer a tool to do that either.

At least it is very good to know what is necessary to get the modem to
work in theory and I can go on trying to resolve the issue. So thank you
for looking into this!

Kind regards,

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