Network-manager/Modem-manager snap possible bug?

snap
1

I’m trying to make a consistent connection to a cellular network using a Quectel EC25-A modem. The problem I’m having is, at startup, the network-manager snap fails to connect to the modem (log below). The weird thing is that it doesn’t happen on every bootup. From what I’ve observed so far, when I do a warm boot (using sudo reboot) the modem connects successfully every time. The problem occurs (inconsistently) on cold boots. I looked around a bit and found this bug (which is my main suspect at the moment). Whenever the modem fails to connect, I get the “invalid bearer IP configuration” error. I’m using UC18 btw.

Sep 03 16:01:55 linux NetworkManager[927]: <info>  [1599148915.5577] policy: auto-activating connection 'CELLULAR'
Sep 03 16:01:55 linux NetworkManager[927]: <info>  [1599148915.5639] device (cdc-wdm0): Activation: starting connection 'CELLULAR' (8af051c3-905e-49f4-bdc4-fb1d0654c76e)
Sep 03 16:01:55 linux NetworkManager[927]: <info>  [1599148915.5652] device (cdc-wdm0): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
Sep 03 16:01:55 linux NetworkManager[927]: <info>  [1599148915.5689] device (cdc-wdm0): state change: prepare -> need-auth (reason 'none', sys-iface-state: 'managed')
Sep 03 16:01:55 linux NetworkManager[927]: <info>  [1599148915.5841] device (cdc-wdm0): state change: need-auth -> prepare (reason 'none', sys-iface-state: 'managed')
Sep 03 16:01:56 linux NetworkManager[927]: <info>  [1599148916.2557] modem["cdc-wdm0"]: modem state changed, 'enabling' --> 'enabled' (reason: user-requested)
Sep 03 16:02:00 linux NetworkManager[927]: <info>  [1599148920.4227] modem["cdc-wdm0"]: modem state changed, 'enabled' --> 'searching' (reason: unknown)
Sep 03 16:02:42 linux NetworkManager[927]: <info>  [1599148962.8436] modem["cdc-wdm0"]: modem state changed, 'searching' --> 'registered' (reason: unknown)
Sep 03 16:02:43 linux NetworkManager[927]: <info>  [1599148963.1666] modem["cdc-wdm0"]: modem state changed, 'registered' --> 'connecting' (reason: user-requested)
Sep 03 16:02:43 linux NetworkManager[927]: <info>  [1599148963.5781] modem["cdc-wdm0"]: modem state changed, 'connecting' --> 'connected' (reason: user-requested)
Sep 03 16:02:43 linux NetworkManager[927]: <warn>  [1599148963.5866] modem-broadband[cdc-wdm0]: failed to connect modem: invalid bearer IP configuration
Sep 03 16:02:43 linux NetworkManager[927]: <info>  [1599148963.5868] device (cdc-wdm0): state change: prepare -> failed (reason 'config-failed', sys-iface-state: 'managed')

Do I have to make a snap that includes this shell script to get around this problem? Does anyone know if there is one already made? Thanks

#!/bin/bash
mmcli -m 0 -b 0 --connect
ifconfig wwan0 up
mmcli -m 0 -b 0
dhclient -d wwan0 &
echo "nameserver 8.8.8.8" >> /etc/resolv.conf

Snap versions:

core18                20200724        1889  latest/stable  canonical✓     base
modem-manager         1.10.0-4        416   1.10/stable    canonical✓     -
network-manager       1.10.6-8        593   1.10/stable    canonical✓     -
snapd                 2.45.3.1        8792  latest/stable  canonical✓     snapd
2

@mike-batbayar note that what the script does is using directly MM to start a connection, so you will not be able to handle it from NM anymore.

It would be interesting if you set both NM and MM debug flag with

$ snap set network-manager debug.enable=true
$ snap set modem-manager debug.enable=true

and collect the full journal after reproducing the bug. Please attach it to this bug, which seems to be the same.

It would be also good to try with the newest NM/MM snaps and check if the result is the same:

$ snap install --channel=20/beta network-manager
$ snap install --channel=20/beta modem-manager
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