System clock cannot sync with hardware clock on boot

The system clock cannot sync with hardware clock on boot if change the system date to a time before the 2021-09-15, below is the commands I used to change the system time.

localhost:~ # date -s “2021-01-01 00:00:00”; hwclock -w
Fri 01 Jan 2021 12:00:00 AM +08
localhost:~ # date; hwclock
Fri 01 Jan 2021 12:00:10 AM +08
2021-01-01 00:00:10.796290+08:00

After reboot, the system clock reset to “2021-09-15 20:00:00”, but the hardware clock is keep to “2021-01-01 00:01:17”.
If I use above commands to set the system date to a time after the 2021-09-15, there is no any problem, hardware clock and system clock remains the same.
Any ideas?

Maybe your hardware/firmware is not able to handle that? You do not tell anything about the hardware, but I doubt many here will know if a specific system has such hardware/firmware restrictions (not being able to go before 2021-01-01. must however be a rather new system in that case).

BTW, welcome to these forums. And to begin with we have the following:
There is an important, but not easy to find feature on the forums.

Please in the future use CODE tags around copied/pasted computer text in a post. It is the # button in the tool bar of the post editor. When applicable copy/paste complete, that is including the prompt, the command, the output and the next prompt.

An example is here: Using CODE tags Around your paste.

Sorry, I think I did not read your post carefully enough.

The hardware clock is OK.

But the system clock goes to 2021-09-15.

Was there something particular on that date? Maybe your installation? I can imagine that the system has problems in being on a date/time earlier then all date stamps it has already.

Any NTP client running?

I tried another machine, did the same thing, after reboot, the system clock reset to “2021-04-27 20:00:00”.
I couldn’t think up anything related to the date being reseted, these machines installed only few days ago.
And no any NTP daemon running in the background.
If you have a 15SP3 OS installed on your side, you could try it see the problem if exists.

No I haven’t. I have Leap 15.3. And you choosed the prefix of the title of this thread also with Leap 15.3

That brings us to the following. These are the openSUSE forums. Are you sure you use openSUSE. It now looks as if you have SLES (or SLED). And that is not what these forums are about.

To save time. In case you use SLE, better go to