Tine 2.0 is an open source software from Metaways, which combines groupware and customer relationship management (CRM).
CalDAV/CardDAV path: / (e.g. https://your.server/)
No CardDAV contact group support. Choose "per-contact categories" as contact group method to minimize problems.
See also: Thunderbird Cal- & CardDAV synchronisation (Tine 2.0org Wiki)