Calendar Sync Not Working

Dear NC Community,

Recently I have migrated to a new set of user devices and the calendar syncs had to be re-added to these devices.

Unfortunately though I have been having issues with my calendar syncs.

  1. On the phones, only a partial calendar comes through.
  2. On mozilla thunderbird with lightning a sync cannot be established whatsoever.

I have tried both the normal shown DAV address and the iOS/OSX DAV address.

The phones do not give any errors, the lightning sync complains that the address is a DAV link, but not CalDAV.

See screenshot:


Could you guys help me debug this problem? Thanks in advance!

Kind regards

P.S. Alternatively or in addition it would be nice to have the ability to export a calendar manually to a common file format, so that I can import it manually on needed devices. Temp workaround, but no fix.