ModemManager 1.16.2 connection issue for EM7455 Sierra Modem

[Alejandro Vega]

Hello,

After making more tests and checking the logs more carefully I have found
differences between the connection sequence , specifically regarding the
bearer options.
When a bearer is created with no auth options, like following the next
command  ( 'allowed-auth' methods are not set):

*mmcli -m 0 --create-bearer="apn=myapn,user=myuser,password=
mypassword,ip-type=ipv4"*

If we try to connect afterwards using the recently created bearer:

*mmcli -m 0 -b 0 -c*

Behaviour in ModemManager 1.10:



*ModemManager[5096]: <debug> [1625232197.783697] Using default (PAP)
authentication methodModemManager[5096]: <debug> [1625232197.783715]
Launching ipv4v6 connection with APN*

Behaviour in ModemManager 1.16.2:


*ModemManager[15247]: <debug> [1625483530.597060] [modem0/bearer0] using
default (CHAP) authentication methodModemManager[15247]: <debug>
[1625483530.597085] [modem0/bearer0] launching ipv4 connection with APN
'tib.com <http://tib.com>'*

And this is causing my modem to fail when attempting a connection. *If I
create the bearer in ModemManager 1.16.2 specifying "allowed-auth=pap", it
works. *
Therefore, before it was not needed to specify the authentication method if
it was PAP, now it seems to be a need.

Note that in both versions the "Provisioned contexts" LOG (where the bearer
info appears) is the same, however, when launching the connection there are
differences.

Hope this helps.

Regards,
Alejandro



El dom, 4 jul 2021 a las 23:16, Aleksander Morgado (<
aleksander at aleksander.es>) escribió:

> Hey,
>
> >
> > I have installed ModemManager version 1.16.2 recently in order to use
> the latest functionalities and I have been experiencing an issue after
> trying to connect to a custom APN (within a VPN).
> > The issue is that the modem is unable to transition from the registered
> to the connected status and finishes the connection attempt immediately
> just after querying a connection command. Using commercial sims with other
> APNs (which normally don't have user and password, don't know if that
> matters) it does not  happen. I am using a EM7455 Sierra Wireless Modem.
> >
> > Until now , I have been working with ModemManager 1.10.6 under MBIM mode
> and have been able to connect with no problems with different types of sims
> (commercial and custom APNs).
> >
> > Attached tests (MM in Debug mode)
> >
> > 3 x tests with the MM 1.16.2 working under QMI mode (x1) and MBIM mode
> (x2 with different errors) but being unable to connect.
> > 1 x test with MM 1.10.6 working under MBIM mode and same bearer
> configuration  , modem is able to connect
> >
> > In order to create the bearer and make tests I am always using this
> custom APN I mention:
> > mmcli -m 0 --create-bearer="apn=tib.com
> ,user=*******,password=******,ip-type=ipv4"
> > mmcli -m 0 -b 0 -c
> >
> > Is there anything I should consider changing regarding the connection
> attempt ? Shall I perform any additional configuration prior to the
> connection in MM 1.16.2 ?
>
> I don't think you would need anything special, truth be told. If the
> modem was connecting fine with 1.10, it should connect equally fine
> with 1.16.
>
> > I found a thread where similar errors appear
> >
> https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/merge_requests/410
> > but I believe it is already merge into MM 1.16.2
>
> That branch adds support for configuring the initial EPS bearer
> settings in QMI modems, I don't think that would affect in any way
> your issue here.
>
> I'm afraid I don't have time to dig into 4 different connection logs
> to try to find differences between them; could you please do that
> yourself and try to compare the working MM 1.10 MBIM connection
> sequence with the failing MM 1.16 MBIM connection sequence and try to
> find what the differences are? If there are no differences, the
> connection should equally succeed.
>
> --
> Aleksander
> https://aleksander.es
>


-- 
Un saludo.

Alejandro Vega
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