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How to debug NetworkManager issue after suspend/resume in Ubuntu 22.04
****Since upgrading to Ubuntu 22.04 recently, immediately after a reboot I have WiFi to an internet hotspot as I did prior to upgrading.
After suspend then resume, the network is no longer working although the NetworkManager process is running. I've tried various nmcli commands including nmcli networking reload but they time out.
After a while (>15m), sometimes this rectified itself, but generally not until after reboot.
When I shutdown the system I find that it is waiting 90s for a 'stop job' on NetworkManager, so maybe the earlier system suspend is not successful leading the resume to time out while trying to re-enable networking. That is just speculation, I'm not sure how to test that. EDIT: see 'workaround' below for more on this.
Any clues on how to look deeper into this, or ideas as to why suspend/resume should cause problems with NetworkManager?
This is a Dell laptop which has been through at least one earlier full Ubuntu upgrade without this kind of issue.
Updates:
NOT SOLVED: The issue went away for a few weeks, possibly after an update but then returned and has been forcing me to reboot after each resume for the past 10ish days, except for one occasion when I had network after resume.
WORKAROUND: If I stop NetworkManager before sleep and start it after resume everything seems ok. Early days but so far so good. Commands I use are:
sudo service NetworkManager stop
...
sudo service NetworkManager start
So as I suspected the issue seems to be that NetworkManager is not stopping properly when the system is going to sleep (see note above about waiting for a stop job).
UPDATE: After using the above workaround for a few days I forgot, but on restarting everything worked again and has for several days since, much like before. So it is an intermittent issue and I'm not sure of the usefulness of the workaround until it fails again.
QUESTIONS:
- is there a way to modify when/how NetworkManager is stopped/started? I haven't been able to find this myself.
- is there a way to insert my own commands to stop/start on sleep/resume?
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