[Deployment Issue] REST API, socket hang up error

[Ratatinator97]

Hello all :)
Caprover is great first of all and big thanks to this community !
Currently I used it with one-click apps only but I plan to move my webapp on it. Problem is: I struggle deploying the REST API :/

What is the problem?
I cannot connect to REST API.
My app runs on port 3000, In Caprover I mapped the container port (3000) with the server port 3030. Then I allowed the 3030 port in ufw.
The container http port is set to 80 (default) because it is an API only app.

I define the port in the nodejs app with : app.listen(port); with port=3000.
I tried app.listen(port,'0.0.0.0') but doesn't work either.

When I try to make requests to the API I have a Error: socket hang up.
The URL I try is http://mydomain.com:3030/auth/signup

If applicable, content of captain-definition file:
{ "schemaVersion": 2, "imageName": "ratatinator97/pictalk-beta" }
I tried other configs but nothing appears to work, what should I do ?