Extremelly weird network problem

[laserburn2]

This problem started on Ubuntu 22.04 about a year ago and is also present on Ubuntu 24.04 which was cleanly installed on the same PC. Computer is connected by ethernet cable to a home router, some Zyxel given to me by the ISP.

Most times, everything works without any problems. But sometimes on boot Ubuntu won't connect. And here is the strange part: in order to make it work, you have to wait for notification to show that the network connection is not available, close that notification, then unplug the network cable from the router and plug it in another ethernet port on the router. If you change the port before the notification is shown or do not close the notification first, changing the port does not fix the issue. Rebooting the computer or the router often doesn't fix the issue either, only the mentioned workaround is reliable.

I've checked journal messages when this happens and I can't seem to find the problem. My guess is that lower and higher level network tools and systems are possibly quarreling among themselves. Any ideas what could be the problem or what I could check?

[#&thj^%]

If you have IPV6 enabled, try to disabled it first to see if that helps steady your connection.
Do it for both WiFi and Ethernet.

Any better?

If not give this a try: (Now wait for it to disconnect)

journalctl -ef > journal_output.txt

To quit it use>>{Ctrl+Alt+ c}

Might give us a clue

[laserburn2]

If you have IPV6 enabled, try to disabled it first to see if that helps steady your connection.
Do it for both WiFi and Ethernet.

Any better?

I did that now, but I won't know if it had any affect for a long time. It can sometimes take weeks before the issue reappears. The bad thing is that it usually happens when I'm in a rush or I'm eating or something else is happening that I don't have time to deal with the stupid issue. So strange that it started out of a blue and persisted through two LTS editions.

If it helps any, here is the journal from the last boot that it happened.

[#&thj^%]

The bad thing is that it usually happens when I'm in a rush or I'm eating or something else is happening that I don't have time to deal with the stupid issue. So strange that it started out of a blue and persisted through two LTS editions.

Isn't that the way things always turn out, when your most pressed for time.

Your not alone on this matter.

Don't forget the logs, it will show something when or if it happens next .

[laserburn2]

It happened again and this time I believe I might have found the culprit in the journal:

Jul 07 21:57:44 Kassad systemd[1]: NetworkManager-wait-online.service: Main process exited, code=exited, status=1/FAILURE
Jul 07 21:57:44 Kassad systemd[1]: NetworkManager-wait-online.service: Failed with result 'exit-code'.
Jul 07 21:57:44 Kassad systemd[1]: Failed to start NetworkManager-wait-online.service - Network Manager Wait Online.

From what I've been Googling on this, seems I was originally on the right track thinking it's a tools conflict, NetworkManager and systemd-networkd might have a problem running together. Before I start messing about, I'd like an opinion of someone more familiar with Ubuntu networking.

[currentshaft]

My guess is that lower and higher level network tools and systems are possibly quarreling among themselves.

Millions of people use Ubuntu daily and do not experience the issue you describe, so unless you've set up the tools to do that on purpose, that is not the cause.

Next step: figure out what "won't connect" means: do you have an IP address, can you resolve DNS, etc?

[Doug S]

Discalimer: I am not a networking expert. I am a server person and do not use NetworkManager.

From what I've been Googling on this, seems I was originally on the right track thinking it's a tools conflict, NetworkManager and systemd-networkd might have a problem running together. Before I start messing about, I'd like an opinion of someone more familiar with Ubuntu networking.

I thought that it was either one or the other, but not both. The related line from the file posted earlier:

doug@s19:~/tmp/tmp/bla$ grep -i networkd output.txt
Jun 26 01:24:34 Kassad systemd[1]: networkd-dispatcher.service - Dispatcher daemon for systemd-networkd was skipped because no trigger condition checks were met.

showing that networkd was not started. But don't take my word for it, check (of course, in my case it is running):

doug@s19:~/tmp/tmp/bla$ systemctl status systemd-networkd
● systemd-networkd.service - Network Configuration
     Loaded: loaded (/usr/lib/systemd/system/systemd-networkd.service; enabled; preset: enabled)
     Active: active (running) since Sat 2024-06-29 07:58:56 PDT; 1 week 1 day ago
TriggeredBy: ● systemd-networkd.socket
       Docs: man:systemd-networkd.service(8)
             man:org.freedesktop.network1(5)
   Main PID: 809 (systemd-network)
     Status: "Processing requests..."
      Tasks: 1 (limit: 38229)
   FD Store: 0 (limit: 512)
     Memory: 3.5M (peak: 4.0M)
        CPU: 410ms
     CGroup: /system.slice/systemd-networkd.service
             └─809 /usr/lib/systemd/systemd-networkd

Jun 29 07:58:56 s19 systemd-networkd[809]: Enumeration completed
Jun 29 07:58:56 s19 systemd[1]: Started systemd-networkd.service - Network Configuration.
Jun 29 07:58:56 s19 systemd-networkd[809]: enp3s0: Configuring with /run/systemd/network/10-netplan-enp3s0.network.
Jun 29 07:58:56 s19 systemd-networkd[809]: br0: Configuring with /run/systemd/network/10-netplan-br0.network.
Jun 29 07:58:56 s19 systemd-networkd[809]: br0: Link UP
Jun 29 07:58:56 s19 systemd-networkd[809]: enp3s0: Link UP
Jun 29 07:58:59 s19 systemd-networkd[809]: enp3s0: Gained carrier
Jun 29 07:58:59 s19 systemd-networkd[809]: br0: Gained carrier
Jun 29 07:58:59 s19 systemd-networkd[809]: br0: DHCPv4 address 192.168.111.136/24, gateway 192.168.111.1 acquired from 192.168.111.1
Jun 29 07:58:59 s19 systemd-networkd[809]: virbr0: Link UP

[laserburn2]

Seems Doug S was correct in his thoughts. Still don't know how to fix the problem.

nikola@Kassad:~$ systemctl status systemd-networkd
○ systemd-networkd.service - Network Configuration
Loaded: loaded (/usr/lib/systemd/system/systemd-networkd.service; disabled; preset: enabled)
Active: inactive (dead)
TriggeredBy: ○ systemd-networkd.socket
Docs: man:systemd-networkd.service(8)
manrg.freedesktop.network1(5)
FD Store: 0 (limit: 512)


nikola@Kassad:~$ journalctl -u systemd-networkd
-- No entries --

[#&thj^%]

Which do you want to use???

 systemctl status systemd-networkd
○ systemd-networkd.service - Network Configuration
     Loaded: loaded (/usr/lib/systemd/system/systemd-networkd.service; disabled>
     Active: inactive (dead)
TriggeredBy: ○ systemd-networkd.socket
       Docs: man:systemd-networkd.service(8)
             man:org.freedesktop.network1(5)
   FD Store: 0 (limit: 512)

Or

 systemctl status NetworkManager
● NetworkManager.service - Network Manager
     Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; p>
     Active: active (running) since Mon 2024-07-08 10:12:54 MDT; 17min ago
       Docs: man:NetworkManager(8)
   Main PID: 1871 (NetworkManager)
      Tasks: 4 (limit: 16308)
     Memory: 7.9M (peak: 26.3M)
        CPU: 1.150s
     CGroup: /system.slice/NetworkManager.service
             └─1871 /usr/sbin/NetworkManager --no-daemon

Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1030]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1036]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1045]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1046]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1371]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <warn>  [1720455201.1392]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1419]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1428]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1429]>
Jul 08 10:13:21 me-Legion-5-zfs NetworkManager[1871]: <info>  [1720455201.1432]>
lines 1-21/21 (END)

journalctl -u NetworkManager

[laserburn2]

NetworkManager service is up and running. If I'm thinking right, NetworkManager on some occasions for whatever reason decides to wait on systemd-networkd and can't connect? I don't really understand how this works.

I've uploaded the journalctl messages of NetworkManager service from the last problematic boot, maybe someone will understand more why it wouldn't connect. I see that it complains that it can't load the connection profile, but it's not clear why.