More info: I switched to systemd and systemd-timesyncd. During boot the time is synced back and forth multiple times and in the end it stays wrong.
Look at this. See the timestamps for each line. Going back and forth. Feb 04 15:59:06 broken-PC systemd-timesyncd[475]: Using NTP server 78.46.253.198:123 (2.debian.pool.ntp.org). Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.925s/0.016s/0.000s/+0ppm Feb 04 15:59:06 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.914s/0.017s/323.505s/+0pp Feb 04 15:59:06 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.904s/0.015s/792.414s/+0pp Feb 04 15:59:06 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.894s/0.015s/723.371s/+0pp Feb 04 15:59:06 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.885s/0.015s/647.003s/+0pp Feb 04 15:59:06 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.874s/0.016s/560.321s/+0pp Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.864s/0.015s/457.500s/+0pp Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.854s/0.015s/323.501s/+0pp Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.844s/0.015s/0.036s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.834s/0.015s/0.045s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.824s/0.016s/0.029s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.814s/0.015s/0.025s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.804s/0.015s/0.025s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.794s/0.015s/0.029s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.784s/0.015s/0.036s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.774s/0.016s/0.045s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.764s/0.016s/0.030s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.754s/0.015s/0.045s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.744s/0.015s/0.037s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.733s/0.016s/0.030s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.723s/0.015s/0.025s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.713s/0.015s/0.025s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.702s/0.017s/0.030s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.693s/0.015s/0.037s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.683s/0.015s/0.045s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.673s/0.016s/0.030s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.663s/0.015s/0.037s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.653s/0.015s/0.045s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.643s/0.016s/0.029s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.633s/0.015s/0.025s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.622s/0.017s/0.025s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.613s/0.015s/0.030s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.602s/0.016s/0.037s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.593s/0.016s/0.045s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.582s/0.015s/0.030s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.572s/0.015s/0.037s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.566s/0.016s/0.044s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Feb 04 15:44:51 broken-PC systemd-timesyncd[475]: interval/delta/delay/jitter/drift 32s/-855.556s/0.016s/0.029s/+0ppm Feb 04 15:59:07 broken-PC systemd-timesyncd[475]: System time changed. Resyncing. Any idea? Matthias
