Unable to connect with ZTE AC2791 USB modem (19d2:fffe) - wvdial works fine

[Aleksander Morgado]

On Tue, Apr 8, 2014 at 7:57 PM, Nilesh Trivedi <nilesh.tr at gmail.com> wrote:
> ModemManager (version 0.6.0.0, Ubuntu 13.10) is unable to connect to
> internet via ZTE AC2791 USB modem (USB id 19d2:fffe). The device is
> modeswitched correctly, the menu item shows up correct in NM-applet but
> after connecting, it immediately gets disconnected, the UI shows the entry
> as "Label Empty" and cannot be connected again.
>
> Wvdial is able to provide a stable connection with the same device with
> config parameters given as per this blog post:
> http://www.anuragbhandari.com/2011/01/bsnl-evdo-in-linux-the-easy-way/
>

We don't actively support MM 0.6 any more (> 1 year old), truth be
told. MM 1.2 was released some months ago.

Anyway, can you try to get debug logs of both ModemManager and
NetworkManager to see what could be happening? You can follow these
steps:
https://wiki.ubuntu.com/DebuggingModemmanager

If you're into it, maybe you could also try to gather debug logs with
MM 1.0 to see if the issue also happens there. You could do so using
e.g. a LiveCD of Fedora 20 or other distro which ships a more recent
ModemManager. These would be the steps for MM 1.x and NM:
http://www.freedesktop.org/wiki/Software/ModemManager/Debugging

-- 
Aleksander
https://aleksander.es