How do I connect my iOS nextcloud app to my local nextcloud server running on a rasberry pi at 10.0.0.12:8080?

Typing 10.0.0.12:8080 in my browser of a pc works, but typing that in the ‘login url’ on the iphone gets ‘An SSL error has occured…’.

Note: Nextcloud is running in a docker

Any pointers? Thanks!