Does the iPhone update you alarms to account for Time Change (Daylight savings)?

Daylight Saving Time skips an hour in the spring, and has the same hour twice in the fall.

You can’t set an alarm for 02:30 during the spring switch-over, because it isn’t.

You’ll need to set the alarm for 1:30, if you need some number of hours between the alarm and some activity and would otherwise set an alarm for 02:30 if not for the DST change.

Any properly functioning device will update directly from 01:59.59 to 03:00:00, with no intervening seconds, for the spring DST change.

Time and timekeeping is much more complex than most realize:

… https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca

I have tried and failed to set an alarm for a time that does not exist. For example, in most parts of the United States, Daylight Savings Time began at 0200 on March 12. Since the local time went from 0159 to 0300 there was no 0230 on that date, and an attempt to set an alarm or an event for that time would fail. My iPhone would not accept it.

However, it is entirely possible that this limitation was not properly implemented in the Swiss localization in which case it is a localization bug. Unfortunately I do not know if this is the fault of iOS or your cellular service provider. Way back when the iPhones was new I had a similar problem that nearly caused me to miss an appointment. The iPhone did not advance the time properly and it was a mess. Whether that was the fault of my cellular service provider or iOS I will never know.