Digitalocean Deploying Node: Empty reply from server

I am deploying a node app to a digitalocean droplet, at the moment when i run the app with the normal 'node' command it doesn't give me any error, however, when i run it with pm2 start it still doesn't give me any error but, when i try to curl the home page it gives me this:

curl http://localhost:4567
curl: (52) Empty reply from server

My app at the moment is running correctly on port 4567 but in the future i would like to use port 80, so if you can help on this even i would really appreciate. I have already searched around the internet for 2 days but still found nothing, if you need additional details feel free to ask!

EDIT #1:

At the moment i am using Nginx as suggested but it is giving me error 502 Bad Gateway.

EDIT #2

This is my nginx default file:

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

        # SSL configuration
        #
        # listen 443 ssl default_server;
        # listen [::]:443 ssl default_server;
        #
        # Note: You should disable gzip for SSL traffic.
        # See: https://bugs.debian.org/773332
        #
        # Read up on ssl_ciphers to ensure a secure configuration.
        # See: https://bugs.debian.org/765782
        #
        # Self signed certs generated by the ssl-cert package
        # Don't use them in a production server!
        #
        # include snippets/snakeoil.conf;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
        index index.html index.htm index.nginx-debian.html;

        server_name mydomain.io www.mydomain.io;

        location / {
                proxy_pass http://localhost:4567;
                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;
        }

        # pass PHP scripts to FastCGI server
        #
        #location ~ \.php$ {
        #       include snippets/fastcgi-php.conf;
        #
        #       # With php-fpm (or other unix sockets):
        #       fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;
        #       # With php-cgi (or other tcp sockets):
        #       fastcgi_pass 127.0.0.1:9000;
        #}

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #       deny all;
        #}
}

My server is running with an ssl certificate if this helps solving the issue.

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