Bug#1080056: systemd-timesyncd: system clock goes out of sync, despite service being enabled and active

[Ralf Jung]

Package: systemd-timesyncd
Version: 256.4-3
Severity: normal

Dear Maintainer,

some time ago, syncing my Laptop clock seems to have stopped working. I can tell
how it slowly drifts away from other, radio-controlled clocks in my apartment.

This is despite systemd-timesync being set up for automatic synchronization:

$ timedatectl 
               Local time: Fr 2024-08-30 08:58:25 CEST
           Universal time: Fr 2024-08-30 06:58:25 UTC
                 RTC time: Fr 2024-08-30 06:58:25
                Time zone: Europe/Zurich (CEST, +0200)
System clock synchronized: no
              NTP service: active
          RTC in local TZ: no

$ systemctl status systemd-timesyncd.service 
● systemd-timesyncd.service - Network Time Synchronization
     Loaded: loaded (/usr/lib/systemd/system/systemd-timesyncd.service; enabled; preset: enabled)
     Active: active (running) since Sun 2024-08-18 08:34:18 CEST; 1 week 5 days ago
 Invocation: 7bd1c1b03524445c8d9e2e6fcb5bb1ba
       Docs: man:systemd-timesyncd.service(8)
   Main PID: 978 (systemd-timesyn)
     Status: "Idle."
      Tasks: 2 (limit: 38086)
     Memory: 1.1M (peak: 3.4M swap: 824K swap peak: 944K)
        CPU: 3.364s
     CGroup: /system.slice/systemd-timesyncd.service
             └─978 /usr/lib/systemd/systemd-timesyncd

Manually restarting systemd-timesyncd.service seems to trigger a sync.

$ sudo systemctl restart systemd-timesyncd.service
$ timedatectl 
               Local time: Fr 2024-08-30 08:59:19 CEST
           Universal time: Fr 2024-08-30 06:59:19 UTC
                 RTC time: Fr 2024-08-30 06:59:19
                Time zone: Europe/Zurich (CEST, +0200)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

Note how "System clock synchronized" switched to "yes". Manual comparison with a
radio-controlled clock also confirms that they are in sync now. But obviously, I
shouldn't have to manually restart this service to get it to synchronize the
clock.

Unfortunately I have no idea how to even debug this.

Kind regards,
Ralf

-- System Information:
Debian Release: trixie/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.10.3-amd64 (SMP w/20 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd-timesyncd depends on:
ii  libc6              2.39-6
ii  libsystemd-shared  256.4-3
ii  systemd            256.4-3

systemd-timesyncd recommends no packages.

systemd-timesyncd suggests no packages.

-- no debconf information