I have a REST endpoint written using WEBAPI. Dates are serialized using the Microsoft format (ms from 1970-01-01) written as a huge number like Date(1443330000000+0200) which is 2015-09-27 05:00 + 2h (07:00). On the mobile side I have JSON.net to deserialize it again. It works on all phones in the world except for Sony Xperia M (Android 4.3) and Samsung Galaxy Ace 4 (Android 4.4.4). A HTC One running 4.0.4 has no issues.
It returns one hour short. Above example would be parsed to 06:00.
The timezones are identical on all phones.
The problem is that the client only uses Sony Xperia M and they all started to report the wrong time on sep 25th at around 02am. It seems like they correct for wintertime exactly one month early?
Any ideas on what to look for?