could not grab port cdc-wdm0: Cannot add port 'usbmisc/cdc-wdm0', unhandled port

Aleksander Morgado aleksander at
Sun Aug 29 13:31:11 UTC 2021

Hey Juan

> I have a system with MM 1.16.4 (NM 1.20.4) and I'm facing some
> problems with my SIMCOM SIM7600G-H
> In some systems, I get a successful activation of the cdc-wdm0 device
> and the wwan0 interface comes up and in some other systems, cdc-wdm0
> fails to be grabbed/activated and the wwan0 stays down.
> I'm attaching the success and failure logs.
> Any clues on where the issue might lie, or where to look for more
> info, would be really appreciated.

The MM version you're using has a 25s timeout when checking for the
QMI support, which may not be enough for newer devices, which take a
looong time to respond in the QMI port.

You may just need this patch
which was released with MM 1.16.6.


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