Android app "could not find host"

I have a little darling running debian 10 and nextcloud 17. I did it based on Carstens guide except I didnt install anything from outside repositories.

The whole login behaviour is a bit weird. With two machines I can reach the login page from local ip and on one I cant. I can always reach the login page from outside ip using browser. I have few friends who have tested this is as well. And on top of this when trying to login with the android app (dev or normal from f-droid) from local or from outside ip it never works.

When you type in the server address and hit enter it immediately prompts a message “Could not find host”. Im at lost with this.

Maybe someone would know whats happening?

Cheers!

So where is the server located? What IP address do you try?

Location: home. I use the same url that I use to login with browser. It works just fine with browser.