Angular returns index.html when calling nodejs api with Nginx reverse proxy

Question

Angular always returns the index.html file content as a response (instead of JSON data) when calling NestJS (NodeJS) APIs with an Nginx reverse proxy when I access to my webapp from a public IP x.x.x.x but when I access it from localhost (same machine where Nginx is installed), everything works well.

Here is my nginx.conf content:

server {
    listen      80;
    listen [::]:80;

    server_name _;
    root   C:/Project/front;

    location / {
        index index.html;
        try_files $uri $uri/ /index.html;
    }

    location /api/ {
        rewrite ^/api/(.*)$ /$1 break;
        proxy_pass http://localhost:3001/;
    }
    
}

Appreciate your help. Thanks !