How to configure Nginx properly to point to SSL app

I followed the tutorials to setup Nginx and deploy a Node.js/create-react-app. However, there seems to be a problem with my set up that I am unable to figure out. When I navigate to my app at “myapp.com”, it shows the DO hello.js file. That makes my think that my Nginx configuration is wrong.

I have also set up SSL for my app with Let’s Encrypt. Not sure if that’s pertinent information.

Here is my /etc/nginx/sites-available/default:

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!
        #

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 myapp.com www.myapp.com;

        location ^~ /assets/ {
                gzip_static on;
                expires 12h;
                add_header Cache-Control public;
  }

        location / {
                proxy_http_version 1.1;
                proxy_cache_bypass $http_upgrade;

                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
           proxy_set_header Host $host;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto $scheme;

                proxy_pass http://4000;

        }
}

Here is my /etc/nginx/sites-available/myapp.com:

server {

        listen 80;
        listen [::]:80;
        root /var/www/myapp.com/html;
        index index.html index.htm index.nginx-debian.html;

        server_name myapp.com www.myapp.com;

        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;
        }

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/myapp.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/myapp.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}

server {
    if ($host = www.myapp.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = myapp.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


        listen 80;
        listen [::]:80;

        server_name myapp.com www.myapp.com;
    return 404; # managed by Certbot
}

Also, my app’s server.js listens on port 4000.

Any help would be greatly appreciated.

Thanks!