i couldn’t redirect domain names to a specific page in my nextjs app using nginx.

i have a nextjs app running on localhost:3000
i used nginx for domain names redirection
when i point a domain name to ‘/’ everything works fine, but when i point a domain to ‘/demo’ i get errors in the console indicating that static files couldn’t load !
the idea that i got is to associate a domain name to each dynamic page created under ‘/[user-website-name]’ to achieve a multi sites solution.
how can i achieve this using nginx or should i modify the next.config.js file ?

my nginx conf

worker_processes  1;

events {
    worker_connections  1024;
}

http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile        on;
    keepalive_timeout  65;

    # HTTPS servers
    server {
       listen       443 ssl;
       server_name  domain.com www.domain.com;

       ssl_certificate      www.domain.com.crt;
       ssl_certificate_key  www.domain.com_key.txt;

       ssl_session_cache    shared:SSL:1m;
       ssl_session_timeout  5m;

       ssl_ciphers  HIGH:!aNULL:!MD5;
       ssl_prefer_server_ciphers  on;

        location / {
            proxy_pass http://localhost:3000;

            proxy_http_version 1.1;

            proxy_set_header Upgrade $http_upgrade;

            proxy_set_header Connection 'upgrade';

            proxy_set_header Host $host;

            proxy_cache_bypass $http_upgrade;
        }
    }

    server {
       listen       443 ssl;
       server_name  domain.com www.domain.com;

       ssl_certificate      www.user-created-domain.com.crt;
       ssl_certificate_key  www.user-created-domain.com_key.txt;

       ssl_session_cache    shared:SSL:1m;
       ssl_session_timeout  5m;

       ssl_ciphers  HIGH:!aNULL:!MD5;
       ssl_prefer_server_ciphers  on;

        location / {
            proxy_pass http://localhost:3000/user-created-website-name;

            proxy_http_version 1.1;

            proxy_set_header Upgrade $http_upgrade;

            proxy_set_header Connection 'upgrade';

            proxy_set_header Host $host;

            proxy_cache_bypass $http_upgrade;
        }
    }
}

next.config.js

const path = require("path");
/** @type {import('next').NextConfig} */
const nextConfig = {
  reactStrictMode: true,
  swcMinify: true,
  sassOptions: {
    includePaths: [path.join(__dirname, "styles")],
  },
};

module.exports = nextConfig;