This helped me resolve:
Was not using the correct port
so i got a synology NAS. I got my calender connected to my phone via carddav. works perfectly fine and there even is a flag with carddav.
reaching it via https://name.synology.me:5001/carddav/USERNAME
BUT, if i do as described to connect to my contacts, there is no flag carddav but the exact same flag to my caldav.
so i want to reach out to my contacts but am only finding my calender via the wrong port, what is happening here and how can i fix that?