Sierra EM7455 not recognized

Samo Ratnik samo.ratnik at
Sun Jun 26 19:01:51 UTC 2016

Hey everyone,
Some good news and some bad news. The good news is that I got the thing
working. I'm using Arch's "stock" NetworkManager and ModemManager and the
AUR packages mentioned above. I simply issue the "sudo qmicli
--device-open-mbim -d /dev/cdc-wdm0 --dms-set-fcc-authentication" command
and then restart the ModemManager with NetworkManager running all the time.
I disabled wifi and bluetooth in the NetworkManager (don't know if this is
relevant in any way) and created a "Mobile Broadband" configuration for my
mobile operator which I open.

The bad news is that the thing is *very* flaky. When issuing the "qmicli
--device-open-mbim ..." I often get various errors. The ones that I got are
enumerated here:

And even when that works okay I have to restart the ModemManager *a lot* to
get a working ping. Sometimes I even shutdown the computer when I do more
than 10 ModemManager restarts. Here's a journalctl output of a session
where I had to issue the qmicli command twice and then the ModemManager
restart worked in the first try:

I can post journals of my further tries or email them to someone if anyone
finds them useful. And thanks again for all the help!

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