DAVx⁵ has been successfully tested with DAViCal.

DAViCal is a server for calendar sharing. It is an implementation of the CalDAV protocol which is designed for storing calendaring resources (in iCalendar format) on a remote shared server.

DAVx⁵ settings

Base URL: /caldav.php/<your.user.name>/ (e.g. https://your.server/davical/caldav.php/exampleusername/)

Contact group method: groups are separate VCards (or the method used by your other clients)

Configure well-known URLs so that you don't have to enter the whole path (recommended).