Calendar sync

Hello, I have managed to sync my iPad calendar to my iDoceo, all apart from a Friday… we have a two week timetable but this ends on a Thursday on iDoceo calendar link but ends on a Friday on the calendar… see attachment where you can see A Week doesn’t appear on Friday even though it does on the calendar. This is the same every Friday. I’ve checked everything I can think of,
Can anyone help?

Bonjour,
Comment avez vous fait je vous prie pour synchroniser calendrier avec Protons ?
Johann