Scheduler not running for arbitrary intervals

Hi all,

I have a very strange behavior of the scheduler in my system.

There are arbitrary intervals during which the scheduler simply does not execute any jobs.
I noticed because e-mails were not fetched into the system.

After about 20 hours, the scheduler started to run again, and e-mail came in as usual.

After verifying the scheduler log, I noticed that we had multiple intervals where the scheduler stopped executing and then restarted.

Any idea, why this might happen?

Best regards,