Disconnect on Data Transfer

[John Marrett]

Reinhard,

Thanks for getting back to me so quickly, much appreciated.

without Qualcomm diag logs on the MC7354 when the problem occurs it might
> be very hard to find the root cause. In order to obtain them you would
> probably have to define a custom udev rule to make ModemManager ignore
> the diag port and also ask Sierra Wireless to provide you with their
> Qualcomm logging frontend.
>

Sierra Wireless has previously made reference to a "DM capture" tool that
will collect logs from the modem, this tool creates swi files that need to
be decoded by Qualcomm support. Is this what you are referring to? Are
there open tools I could use to decode these files?


>
> Alternatively you could also check whether one of the following makes the
> problem go away:
>
> 1. Switch to Linux kernel 4.5 or newer for testing so that ModemManager
>    uses Raw IP mode for QMI.
>
>
I'll see if I can get access to a release with a newer kernel.


> 2. Apply commit 245d21190aec547c0de64f70c0e6de871c185a24
>    ("qmi_wwan: set FLAG_SEND_ZLP to avoid network initiated disconnect")
>    if not already present in the qmi_wwan version you use.
>
> 3. Reduce the MTU size to 1280 for testing.
>
>
AT&T also spoke about reducing MTU when we were experiencing issues; I
wasn't able to get an reason for why they thought it would help. Why do you
suggest lowering the MTU to 1280?

Thanks again,

-JohnF
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