PPP modem differences

[Colin Helliwell]

> On 22 March 2017 at 13:50 Dan Williams <dcbw at redhat.com> wrote:
> 
> On Wed, 2017-03-22 at 13:23 +0000, colin.helliwell at ln-systems.com
> wrote:
> 
> > I know this might not be an issue with MM, but as there's also a lot
> > of
> > modem-savvy people here.. :)
> > 
> > I've got the same system trying to make a ppp connection via MM. I'm
> > using
> > the same SIM card, and running
> >  mmcli -m 0 --simple-connect="apn=mobile.o2.co.uk"
> >  pppd nodetach call provider
> 
> Quite puzzling; I haven't seen these kinds of requests originating from
> the modem before. But some thoughts:
> 
> 1) same modem hardware? If so, same firmware? If not, I wouldn't be
> surprised that different hardware is working differently, though I
> haven't seen these kind of challenges from the modem before.
> 

Nope - both Cinterion, but different models.

> 2) Modems do store some state in NVRAM. Sometimes that can include
> things like the default authentication mechanism (CHAP vs. PAP vs.
> none). Perhaps your second device has a different setting for that PDP
> context; what does AT+CGDCONT=? say between them?
> 

I'd looked at those, and they seemed sane (as far as they go).
Working:
mmcli -m 0 --command="AT+CGDCONT?"
response: '+CGDCONT: 1,"IP","wap.vodafone.co.uk","0.0.0.0",0,0
+CGDCONT: 2,"IPV4V6","wap.vodafone.co.uk","",0,0'
[MM log showed cid 1 being used in the AT*99]

Non-working:
mmcli -m 0 --command="AT+CGDCONT?"
response: '+CGDCONT: 1,"IP","wap.vodafone.co.uk","0.0.0.0",0,0'

I'm not sure where/when the 0.0.0.0 got inserted in the Working one. It *wasn't* there to start with on the non-working one, so when I saw that diff I re-configured to add it. But not working with nor without that field.

> I assume these are Cinterion devices? Might be able to use some
> Cinterion AT commands to figure out if there are settings differences.
>