Calendar Publishing Host; weekdays shifted


I'm using Calendar Publishing Host for a few years now in our firm. Since we upgraded to GW2014 there is a strange behavior.

The weekdays are shifted. Week starts at Monday (the Netherlands). Sunday is displayed as first day of the week, appointments however are displayed on the number of the day that week.
E.g. if there is an appointment on Monday, first day of the week, it's displayed on Sunday, for that is how Publishing Host will start the week.
Have been playing around with settings. Doesn't change.

Webaccess does display correct:

Shifted background in Publishing Host:

Does anyone encountered the same? And is there a way yo correct this?