502 bad gateway error when deploying to nginx web server - node.js

Question

I built a react app using the create-react-app and npm run buildcommands and connected it to node with server.jsfile in the directory created by create-react-app.
When running the command node server locally it works perfectly fine however when I pushed the changes to my nginx server I started to get a 502 bad gateway status. Why is this happening? Node is running when I get this error.
Here is the server.js code
onst express = require('express');
const path = require('path');
const app = express();
app.use('/js', express.static(path.join(__dirname, 'src/')));
app.use('/css', express.static(path.join(__dirname, 'src/')));
app.use(express.static(path.join(__dirname , '/public/build')));
// Handles any requests that don't match the ones above
app.get('/', (req,res) =>{
res.sendFile(path.join(__dirname , "/public/build/index.html"));
});
const port = process.env.PORT || 5000;
app.listen(port);
console.log('App is listening on port ' + port);
the error log
[error] 7422#7422: *4477 connect() failed (111: Connection refused) while connecting to upstream, client: 162.84.158.175, server: anthonyjimenez.me, request: "GET / HTTP/2.0", upstream: "http://127.0.0.1:3000/", host: "anthonyjimenez.me"
and the config file
http {
##
# Basic Settings
##
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
# server_tokens off;
# server_names_hash_bucket_size 64;
# server_name_in_redirect off;
include /etc/nginx/mime.types;
default_type application/octet-stream;
##
# SSL Settings
##
ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
ssl_prefer_server_ciphers on;
##
# Logging Settings
##
access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;
##
# Gzip Settings
##
gzip on;
# gzip_vary on;
# gzip_proxied any;
# gzip_comp_level 6;
# gzip_buffers 16 8k;
# gzip_http_version 1.1;
# gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;
##
# Virtual Host Configs
##
include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}

Answer 1

go to /nginx/sites-enabled/default and add the following blocks. You will have to tell Nginx and forward this request this way
server {
listen 443 ssl ;
ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; //ssl
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; //ssl
index index.html index.htm index.nginx-debian.html;
server_name example.com;
location / {
proxy_pass http://localhost:3001; //Your port goes here
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;
}
}