Create dummy Appl. Server on DWP with Firewall

Dears,
I have a DWP, I've configured the firewall some days ago:

!image|690x227

I then installed a dummy npm/express server running on port 3000.
If I call it from the DWP, it answers correctly.

If I try from my home PC, or from another different DWP, it fails (impossible to connect to remote server, probably is just a timeout).

I tried executing the call using:
- the dwp IP
- the service name, vpsXXXXXX.ovh.net
- the reverse address, XXX.ip-XXX-XXX-XXX.eu

Result is always the same, no connection.

Am I missing something? Is the DWP (VPS 2018 SSD 2) not configured by default to be reachable from Internet?
Is this configurable?

I wasn't able to find a manual or a thread to follow and understand what is the problem.

Thanks,
Giorgio