data connection lost

Bug #1955707 reported by Slark Xiao
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Cyborg (OpenStack)

Bug Description

    For Qualcomm based modem devices, with PCIE interface, and mhi driver based on kernel 5.13.0, it will lose data connection. Details as below:

        1) Can NOT connect to Internet
        2) /dev/wwan0p1QCDM, /dev/wwan0p2MBIM, /dev/wwan0p3AT NOT response

    Reproduce steps
        1) Connect Internet via cellular
        2) Do speedtest( or download a 1GB file (

    Recovery method
        Only can be recovered by cold boot(Power off, then power on).

        It can NOT be reproduced in Windows 10/11.

Revision history for this message
Freeman Zhang (zhanggyb) wrote :

(a) It's better that the modem's FW can provide the log including debug message to describe which event/command was sent from the driver to cause the modem's FW to crash.
(b) Enable the debug in ModemManager to collect the log to know the last command sent to the modem

For Ubuntu Core, to enable the modem-manager snap:
$ sudo snap set modem-manager debug.enable=true
$ sudo snap restart modem-manager

Revision history for this message
Slark Xiao (slarkxiao) wrote :

  Actually modemmanger log won't provide help when issue happened. I attached a host dmesg log for a reference.

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