Re: new problems with connecting with an LTE modem

[Bhima <bhima pandava gmail com>]

Hey thanks for the quick response!

I'm not able to use the qmi-network helper script anymore because it 
always fails:

Starting network with 'qmicli -d /dev/cdc-wdm0 
--wds-start-network=drei.at  --client-no-release-cid'...
[20 May 2016, 19:28:07] -Warning ** Error reading from istream: Resource 
temporarily unavailable
error: couldn't create client for the 'wds' service: CID allocation 
failed in the CTL client: Transaction timed out

So I've been using mmcli, like this: "sudo mmcli --verbose 
--simple-connect="apn=drei.at,ip-type=ipv4" -m 0"

The connection that gets made is pretty bad... like 5% of bandwidth I'm 
used to. The signal strength reported by mmcli status report is "67" but 
I've got no idea what that really means (and it's not like I've changed 
the hardware or even moved it recently).

I'm wondering if the modem gets half way through getting configured and 
making the connection with another, perhaps new, mechanism and now 
trying to go through the process twice is what is making it not work.

On 20/May/16 6:21 pm, Dan Williams wrote:
> On Fri, 2016-05-20 at 16:10 +0200, Bhima wrote:
> > Hi Guys!
> >
> > I'm having problems with a Sierra MC7710 LTE modem, running in a
> > Soekris
> > Net6501, after a recent update to Ubuntu 16.04 to the 4.4.0-22-
> > generic
> > kernel.  For the past few years I've been using the qmi-network
> > helper
> > script to connect cdc-wdm0, which in turn created a wwan0 port.  Now
> > that's all gone pear shaped and I've gone around in circles trying
> > figure out what's gone wrong.
> >
> > looking in dmesg, I see that wwan0 is actually getting renamed to
> > wwp2s2f3u3i8, which is confirmed by status returned by "mmcli -m 0"
> > (ports: 'ttyUSB0 (qcdm), ttyUSB2 (at), cdc-wdm0 (qmi), wwp2s2f3u3i8
> > (net)').  I can get a dhcp address on 'wwp2s2f3u3i8' but the
> > throughput
> > on the resulting channel is severely constrained.
> >
> > So now I'm wondering what exactly the proper way to configure and
> > use
> > this modem from the command line these days.
> Probably the same way you always have; as you've found the interface is
> now named something different, which is happening because of udev's
> interface renaming policy in the updated Ubuntu release.  But it's
> still the same interface as before and should work the same way as
> before.
>
> How much of a drop in throughput have you've found?  Any throughput
> drop will likely be related to kernel driver changes in qmi_wwan and
> the kernel USB layer, as opposed to something in ModemManager itself or
> the qmi-network script.  When the througput is bad, what is the signal
> strength of LTE connection?
>
> Dan