DAVx⁵ has been successfully tested with Baïkal.
Baïkal is a lightweight CalDAV + CardDAV server, based on SabreDAV.
Base URL: /dav.php/ (e.g. https://server.example/baikal/dav.php/) or
Base URL: /html/dav.php/ (e.g. https://server.example/baikal/html/dav.php/) (in newer versions)
Contact group method: groups are separate VCards (or the method used by your other clients)
Last updated: 13 Oct 2020