[SOLVED] My Sierra Wireless EM7345 4G LTE drives me crazy!

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Hansl
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[SOLVED] My Sierra Wireless EM7345 4G LTE drives me crazy!

Post by Hansl » Thu Jan 18, 2018 9:54 am

I've got a nice Lenovo T450s Thinkpad with an internal Sierra Wireless EM7345 4G LTE modem.  I've installed LMDE2 Mate and set everything up, Kernel and some graphics stuff from jessie-backports.  As a last step I wanted to set up Mobile Broadband (with AldiTalk/Medion Mobile) and I just can't get it to work.

More details below, in short: I have the latest firmware and switched to mbim mode.  The modem registers to the network, I can connect to it with network-manager, the icon and info shows a HSUPA connection, gnome-nettool shows a connection and a few packets trickling by — but I get no internet access.

On Windows 10 I got a working connection.  With the live LMDE2 installer USB stick I do get a working connection (after setting up mbim mode), so the hardware and the SIM/provider is ok. 
With my actual LMDE2 installation, no access. Huh?

I've noticed the following which may be the real problem: after disconnecting WLAN and having started the broadband connection, route shows nothing (except its headline) and hangs.  What am I missing?


Some background, may help others:  The EM7345 seems to be infamous for buggy firmware, one should install the latest.  Unfortunately this needs Lenovo's Windows, Lenovo Service Bridge, some working connection, and having a working SIM card inserted!  So… booting the live LMDE USB, saving the LMDE disk image (twice, for security), restoring the Win disk image.  Pulling all Windows and Lenovo updates, including this firmware, BIOS, the infamous Intel Management Engine etc.  Saving twice the changed Win image, restoring the LMDE image again — takes 1.5 TB transfer and a whole day all in all. Should have done a dual boot install…
Have now firmware FIH7160_V1.2_WW_01.1616.01 ; V1.2 seems essential.

On Linux, the EM7345 seems to need mbim mode. Manual one-shot:

Code: Select all

sudo rmmod cdc_mbim 	# uses 
sudo rmmod cdc_ncm
sudo modprobe cdc_ncm prefer_mbim=Y   # restart with this option
sudo modprobe cdc_mbim   # restart 
echo '1-4' | sudo tee /sys/bus/drivers/usb/unbind   # power-cycle the modem 
echo '1-4' | sudo tee /sys/bus/drivers/usb/bind     # at USB bus 1 device 4  
ls /dev    # now must show a newly added  cdc-wdm0 
For permanence, created a   /etc/modprobe.d/em7345.conf   containing —
options cdc_ncm prefer_mbim=Y

All this was necessary to get the modem to connect at all. 

Thanks to the following tips (caution, somewhat outdated)!
https://forums.lenovo.com/t5/ThinkPad-X ... -p/2046489
http://linux-thinkpad.10952.n7.nabble.c ... 21273.html
https://zukota.com/all-sierra-wireless-em7345-firmware/
https://thinkpad-forum.de/threads/19037 ... nter-linux
Last edited by Hansl on Thu Jan 18, 2018 3:43 pm, edited 1 time in total.

Hansl
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Posts: 103
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Re: My Sierra Wireless EM7345 4G LTE drives me crazy!

Post by Hansl » Thu Jan 18, 2018 10:04 am

Hmm… /etc/resolv.conf seems to be stuck at the previous WLAN connection.

Hansl
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Joined: Fri Dec 09, 2011 3:50 pm

Re: My Sierra Wireless EM7345 4G LTE drives me crazy!

Post by Hansl » Thu Jan 18, 2018 3:41 pm

Just connected this machine to another wired LAN — also connected with no access. Some digging and comparing to an older machine showed that here /etc/resolv.conf was a regular file, dating from the day of installation and containing static data from that first connection. (That was wired LAN, with the same nameserver as the subsequently added WLAN connection, but of course not those of the broadband connection or other LANs.)

Whereas in the working machine /etc/resolv.conf is a symlink to /run/resolvconf/resolv.conf which is dynamically created/updated.  So I replaced the static file with a symlink and now all is fine — thus SOLVED. Just how could that have happened?

So this last connection problem was not with the EM7345 at all. 
But the previous settings (firmware >= V1.2, and mbim mode as explained above) were and still are necessary to get the EM7345 up and connecting at all, it did not work with standard LMDE install.  Maybe this helps someone else.

Hansl
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Posts: 103
Joined: Fri Dec 09, 2011 3:50 pm

Re: [SOLVED] My Sierra Wireless EM7345 4G LTE drives me crazy!

Post by Hansl » Fri Jan 19, 2018 5:57 am

Well, that's a funny thing:  Looking at several LMDE machines of different installation ages (from first LMDE upgraded to LMDE2, to recent bare installations from 2017-01 iso), I find machines with symlinks /etc/resolv.conf → /run/resolvconf/resolv.conf and also ones with no /run/resolvconf/resolv.conf where /etc/resolv.conf is a regular file and kept current.  How comes?

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