1 out of 6 hostnames wont work, why?

I’ve created 6 public hostnames, so I can reach my internal sites from the outside when i’m not home.
5 of the sites works fine, and I can connect to my internal services.
But my nextcloud wont work.

When I try from outside my network, the site times out.
If i go to cmd, I can ping my nextcloud.mydomain.dk, but I still cant connect from a browser

Anybody got an idea?