Calendar issue in Mac - entries older than 1-2 months disapear

[Piotr]

My service provider (webpage, email etc.) is using Open Xchange. I noticed strange issue since about 2 months.
Unfortunately their support is not able to solve this problem and it looks that they blame me for it.
So maybe someone here had similar problems - I will appreciate any advice and idea.
I have issue with CalDAV. We are using Mac, Win and Linux computers and some mobile devices - Android and iOS.
I noticed in May that suddenly all entries from my calendar before April disappeared from our Macs (two separate computers attached to two separate account in our server). I mean - I was able to see only entries/events in calendar since 1st of April. And before I was able to see everything even some very old entries. Strange is that on mobile devices and Linux, Win and web calendar it is visible.
On my Mac I'm using standard Apple Calendar and additionally added for test Thunderbird - and on both the same issue.
Than on 1st of June I noticed that all entries from April disappeared too. So now I can see only entries from May and June.
What is strange - when I will add anything to calendar (on Mac) on for example 1st of February - than after sync, it will disappear from my Mac but it will be visible on any other devices and on web calendar.
This is exactly the same with my own calendar and with shared ones too.

Any advice? Any idea?
What should I say to my service provider? Maybe they have some wrong settings on Open Xchange Server?

[Marc Arens]

Hello,

this behaviour reflects the defaults configured in /opt/open-xchange/etc/caldav.properties

# Appointments and tasks are available via the CalDAV interface if they fall
# into a configurable timeframe. This value specifies the start time of this
# interval, i.e. how far past appointments should be considered. More formal,
# this value defines the negative offset relative to the current date
# representing the minimum end time of appointments to be synchronized.
# Possible values are "one_month" (default), "one_year" and "six_months".
com.openexchange.caldav.interval.start=one_month