Problem with reconnecting when using Ericsson H5321 modem and Aero2 BDI network

[Aleksander Morgado]

Hey,

> >> I have a problem with modemmangager 1.6.8-2ubuntu1 and 1.8.2-1.
> >>
> >> Modem: Ericsson H5321.
> >> Computer: Lenovo ThinkPad X230.
> >> Network: Aero2 BDI (Polish, APN darmowy).
> >>
> >> The network (according to obtained licence for using radio spectrum
> >> frequencies) is obliged to provide a service of a free Internet
> >> access
> >> with a few limits.
> >> One of those limits is an automatic disconnection every (about) 1
> >> hour.
> >> In order to access the Internet again one needs to reconnect and
> >> solve
> >> the Captcha.
> >>
> >> The first problem with the mentioned modem is that the disconnection
> >> is
> >> not visible to the user - the Network Manager works as if the
> >> connection
> >> would be still active - the Network Manager shows the connection as
> >> still active and one needs to disconnect manually as there is no
> >> Internet access.
> > Looks like the modem doesn't indicate disconnection via MBIM Basic
> > Connect Packet Service State.  When you think it's disconnected, could
> > you run:
> >
> > mbimcli -p -d /dev/cdc-wdm3 --query-connection-state=0
> >
> > I'm curious what the "Activation State" property will be when the modem
> > is disconnected.
> >
> > If it reports that the activation state is disconnected, then we
> > probably need to implement support for the MBIM Basic Connect "Connect"
> > notification, or implement polling the state via
> > load_connection_status.
> >
> > Dan
> Hi,
> Here is the result of the command after the Internet access was
> disconnected but claimed as connected by Network Manager (modemmanager
> 1.6.8-2ubuntu1):
> [/dev/cdc-wdm3] Connection status:
>            Session ID: '0'
>      Activation state: 'unknown'
>      Voice call state: 'none'
>               IP type: 'ipv4'
>          Context type: 'none'
>         Network error: 'unknown'
>
> It does not change after manual disconnecting and later reconnecting or
> turning off and on the network in the Network Manager.
>

Looks like we really are missing the notifications reporting the
disconnection then, the module is not sending those it seems. Plus,
the failed attempts to reconnect once disconnected manually, returning
"NoDeviceSupport" are also a good indication that the firmware is not
behaving well.

We could add explicit polling for the connection status but only for
selected devices, as we do with
ID_MM_QMI_CONNECTION_STATUS_POLLING_ENABLE for selected QMI devices.
But that won't solve the issue with the failed reconnection attempts.

> In the meantime I found following the instructions described here solves
> the problem (with the exception that I have ommitted replacing idVendor
> and idProduct as there already was a corresponding rule in the file):
> http://blog2.vorburger.ch/2015/03/fixed-linux-ericsson-h5321gw-3ggpshspa.html
> Not sure if that fixes the problem or only workarounds it, though.

That is switching the module from MBIM to the plain AT+NCM logic used
by the ericsson mbm plugin. I'm sure it makes sense that this logic is
more stable as it's older than the MBIM implementation.

-- 
Aleksander
https://aleksander.es