@max Synchronizing calendars in both directions is a very complex task, and it takes more than just downloading and uploading a single .ics file per calendar. If you have a look at CalDAV and which problems it solves, you will see what the problems are. You will also need a hierarchy: just think about the case that one .ics file contains a certain event, and the other doesn’t. So, does it mean that it has been deleted by the user and should be deleted from the one .ics file, too, or has it just been added and should be added to the other .ics file?
Early calendar entries
The webcal entries are a day before when they should be. I have tried other webcal apps and they put it on the right day.
Thank you for the information!