Problems getting built-in 3G modem (Ericsson H5321gw – USB ID 0bdb:1926) working on my Lenovo X230 (Debian)

Question

I have Ericsson H5321gw WWAN modem (USB ID 0bdb:1926) on my Lenovo X230 laptop. I've got it working momentarily using NetworkManager GUI on Gnome3. Normally I can make it connect for a few minutes only to see the whole device being removed from NetworkManager later by itself. So technically it is working, but somehow the device keeps getting removed after a while (causing disconnection, of course). Initially I thought this might be an issue of USB Autosuspend power saving functionality but I have tried setting it off like so:

for i in /sys/bus/usb/devices/*/power/autosuspend; do echo -1 > $i; done

I have Debian Jessie with 3.10-3-amd64 kernel.

This is an example log from test where I got disconnected right away after connecting: http:// pastebin.com/ bGbTHGri (url pasting limit, sorry)

This is another test where I got disconnected after being connected for about 2 minutes:

• /var/log/kern.log: http://pastebin.com/wkQkkYrA
• /var/log/syslog: http://pastebin.com/Hx8aJqvx

Answer 1

Ok, figured this out. You need to:

sudo cp /lib/udev/rules.d/77-mm-ericsson-mbm.rules /etc/udev/rules.d/ 

and then edit it to add an entry matching your card's lsusb output. That solved this for me.
Full blurb on my http://blog2.vorburger.ch/2015/03/fixed-linux-ericsson-h5321gw-3ggpshspa.html