Thanks to PitaJ I have the solution for anyone else who encounters this problem. Make sure the url in the conf.json is correct. Also make sure that the ip adress is prefixed with http://
I tested some forum software to find the "best one" and so I also tested esoTalk
It based on php instead of nodejs. EsoTalk forum is different to php forum software like smf or phpbb. It's fat free and really fast.
NodeBB is already modern and full of new ideas, but public / private / group conversations and some other esoTalk approaches could also improve NodeBB any more?
The only thing I liked when I used esoTalk was the filtered channels (which was an idea I had pitched to the developer in the beginning when it was pretty new to the scene, however it was implemented brilliantly just as imagined).
The search was pretty powerful with the use of gambits.
The private conversations were cool too.
Other than these 3 things, thats about all that makes it stand out for me.
Spiceworks does some interesting things and has a massive userbase being supported.
Filtered channels and private conversations are a great approach, but I think NodeBB won't go that way in the future.
So esoTalk is an alternative to NodeBB because it's also fast and comfortable to use.
The combination with all the benefits of both would be the absolute best solution...