Problem using GSM modem on Ubuntu 16.04

Question

I justed upgraded to Ubuntu 16.04 LTS. Everything looks fine except the modem.

First, the modem connects but the icon doesn't change. It still shows 'disconnected icon'. Old computer shows right icon after connecting.

2nd, the connection shows 'EDGE' in bracket. On old computer connection shows 'HSPA'. This means browsing on the upgraded ubuntu in nearly impossible.

Lastly, on old computer when I unplug the modem I get the message "Network - disconnected you are now offline". On new version of ubuntu no message appears.

Not sure whether this is a problem with new hardware or with ubuntu. But it's definitely not a problem with the modem since same modem works perfectly on old computer.

Any idea?

Thanks.

Answer 1

I never got to resolve this but took some time to test the modem on different distributions.

The modem doesn't work on following:

1. Ubuntu 16.04
2. Fedora 23
3. openSUSE 13.2
4. Ubuntu 14.04

Modem works on:

1. Kubuntu 16.04
2. Ubuntu 15.04
3. Ubuntu 11.04

I decided to switch from Ubuntu 16.04 to Kubuntu 16.04. Now the modem works perfectly,

Answer 2

Blacklist the qmi_wwan and cdc_wdm kernel modules

Since you are dealing with an older mobile broadband modem (probably a Qualcomm Gobi 1000 or 2000) in combination with a newer Linux kernel, you will need to blacklist the qmi_wwan and cdc_wdm kernel modules when upgrading from (X)Ubuntu LTS 14.04 to (X)Ubuntu LTS 16.04.

The kernel modules qmi_wwan and cdc_wdm are modern interfaces which modemmanager will try in vain to establish a communication with your older 3G modem.

The solution consists in using your favourite text editor with superuser privileges to open

$ sudo nano /etc/modprobe.d/blacklist.conf

and append the following lines:

blacklist qmi_wwan
blacklist cdc_wdm

Reboot and your mobile broadband modem should work again as before.

Answer 3

First, the modem connects but the icon doesn't change. It still shows 'disconnected icon'. Old computer shows right icon after connecting.

Its the new way - the two up/down arrows don't change immediately, but they should change once you start data transfer. In any case, its an experimental feature they are experimenting with, perhaps to emulate the network icons in the smart-phone world. This and your third issue might be fixed by 16.04.01, but it doesn't hamper your work in any way.

2nd, the connection shows 'EDGE' in bracket. On old computer connection shows 'HSPA'. This means browsing on the upgraded ubuntu in nearly impossible.

Your more pressing issue is this - internet speed. This has happened because earlier, Ubuntu used to give you an option in the network-manager's edit connection applet to select a network type such as any, 3G Only, GPRS/EDGE, etc. but it no longer gives since 16.04. By default its the any mode, so you might be getting a slow speed. But you can force it to 3G Only by using a simple configuration change:

Just edit /etc/NetworkManager/system-connections/your_3g_connection file and change network-type to 0 in the [gsm] section, so you can force it to 3G only.

Source: https://askubuntu.com/a/370465/49938