Apple is still grappling with daylight saving time issues after all these years. Some Australian Apple Watch Series 4 owners have reported that their devices are stuck in reboot loops after the country switched to DST this weekend. Apparently, the Activity complication on the Series 4's Infograph Modular face doesn't know how to handle a day that's an hour short -- so long as that complication is active, the smartwatch crashes and restarts until it runs out of power.
Some users have had success changing the face through the Watch app on the iPhone, but the only surefire solution may be to wait until the shortened day is over.
We've asked Apple for comment. While this sounds like a temporary problem, it could be a recurring one as there isn't a fix. DST ends in North America on November 4th, for instance. While it's not certain if the bug applies when you gain an extra hour in the day, Series 4 users might not want to find out first-hand.