nginx svelte django(waitress) external ip no response

Question

I have the following nginx configuration:

// nginx.conf
server {
  listen       8888;
  server_name  xxx.xx.xxx.xx; // my PC's external ip 
  root         html;
}

and I'm running a django/waitress server on xxx.xx.xxx.xx:8072

This is my svelte code fetching data from the django server

const res = await fetch(`http://xxx.xx.xxx.xx:8072/myapp/`);

I built this svelte app and copied the content of the public folder to nginx/html and ran nginx. 'http://xxx.xx.xxx.xx:8888/myapp' gives me no response from the django server.

However, if I fetch from 'localhost:8072' and run the django server on locahost:8072, and configure nginx with server_name 'localhost', this work properly.

Why is this not working with an external IP?

Sorry for my poor English.