Modem not connecting on Ubuntu 16.04 (whereas it did on Ubuntu 14.04)

[Dan Williams]

On Tue, 2016-08-30 at 20:34 +0530, Ajay Garg wrote:
> Thanks Aleksander, for your (as always) detailed and crisp analysis.
> 
> 
> On Tue, Aug 30, 2016 at 8:09 PM, Aleksander Morgado
> <aleksander at aleksander.es> wrote:
> > 
> > On Tue, Aug 30, 2016 at 8:56 AM, Ajay Garg <ajaygargnsit at gmail.com>
> > wrote:
> > > 
> > > The reason turned out that I had disable USB-3.0 support in BIOS.
> > > When I turned it on, the modem started connecting in both 14.04
> > > and 16.04.
> > > 
> > > However, in 14.04 the "wwan" interface appears fine (and after
> > > running
> > > "dhclient" on it, the internet works fine).
> > > However on 16.04, no "wwan" interface appears, even after mmcli
> > > -m 11
> > > --simple-connect="apn=airtelgprs.com" has resulted in successful-
> > > connection.
> > > 
> > > 
> > > A maybe related symptom is that ethernet-interfaces appear as
> > > "eth0" and
> > > "eth1" in 14.04, but as "enp1s0" and "enp2s0" in 16.04. But even
> > > then, NO
> > > ADDITIONAL INTERFACE appears when mmcli -m 11
> > > --simple-connect="apn=airtelgprs.com" has resulted in successful-
> > > connection
> > > on 16.04.
> > > 
> > > Looks very weird; I will be thankful for any help.
> > --simple-connect doesn't make interfaces appear/disappear :) The
> > WWAN
> > interface should be detected and available before you even attempt
> > to
> > run --simple-connect.
> 
> :O :O :O
> 
> Hasn't happened for me on Ubuntu 14.04.2 / 14.04.3 so far, not even
> once in the last 1 month or so I have been working on this. However,
> things have been working fine via the commands I shared in my
> originating email.

Very odd; the net interface should always be present whenever the card
is connected, no matter whether the card is connected or not.

It may not report itself via "ifconfig" because it's not IFF_UP though,
use "ifconfig -a" or 'ip link' to see it.  In 16.04 it'll be named
something like "wwp0s20u4" instead of wwan0 or eth1 or usb1.

> The interface occurs if and only if the --simple-connect runs to
> completion, successfully.
> 
> Should I be worried?

Yes, that's odd.  Run 'ip link' before --simple-connect and see if the
interface is present.

Dan

> > 
> > 
> > Looks like you have now the "predictable network interface names"
> > support in Ubuntu 16.04, coming from systemd:
> > https://www.freedesktop.org/wiki/Software/systemd/PredictableNetwor
> > kInterfaceNames/
> > 
> > This means that you won't have a "wwan0" interface any more; look
> > for
> > something like "ww...."
> > 
> > Anyway, the correct flow is to avoid manually looking for the
> > network
> > interface name. Once you have run "--simple-connect", you'll have a
> > connected "bearer" object reported in ModemManager. The bearer
> > object
> > will tell you, in its details, what interface name you should use
> > and
> > also the specific connection method you're supposed to use (dhcp,
> > static, ppp).
> Thanks for this info Aleksander, I will keep this in mind if I do
> have
> to take the trouble of evaluating a new version :)
> 
> 
> > 
> > 
> > --
> > Aleksander
> > https://aleksander.es
> 
> Thanks and Regards,
> Ajay
> 
> 
>