System clock drifting due to dual-boot

Hi, yes, this is very commonly caused by the two operating systems disagreeing about how the hardware clock is stored.

Windows normally expects the hardware clock to be local time. Many other operating systems expect it to be UTC. When you switch between them, each OS "corrects" the clock from its own assumption, and the time jumps by a few hours.

The clean fix is to make both systems use the same approach. On many Linux dual-boot setups, setting Linux to treat the hardware clock as local time is the simplest path. Also make sure both systems use the same time zone, disable Fast Startup in Windows, and then force a time sync after rebooting. Once the RTC/local-time mismatch is fixed, internet time sync should stop fighting the problem every boot.