Nodejs reverse proxy server (nginx) - node.js

Question

I have already running 2 servers at digital ocean and I installed nginx for webserver and nodejs for app server.
For app server :
Nodeapp Directory : /var/appdata/myapp/
Nodejs app running at 4680 Port;
However in the app server I have couple iptables options(firewall)
IPTABLES Options I did for appserver:
*filter
# Default policy is to drop all traffic
-P INPUT DROP
-P FORWARD DROP
-P OUTPUT DROP
# Allow all loopback traffic
-A INPUT -i lo -j ACCEPT
-A OUTPUT -o lo -j ACCEPT
# Allow ping.
-A INPUT -p icmp -m state --state NEW --icmp-type 8 -j ACCEPT
# Allow incoming SSH, HTTP and HTTPS traffic
-A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
-A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT
# Allow inbound traffic from established connections.
# This includes ICMP error returns.
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# Log what was incoming but denied (optional but useful).
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables_INPUT_denied: " --log-level 7
# Allow outgoing SSH, HTTP and HTTPS traffic
# This is useful because we won't be able to download and install
# NPM packages otherwise and use git over SSH
-A OUTPUT -o eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
-A INPUT -i eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT
# Allow dns lookup
-A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT
-A INPUT -p udp -i eth0 --sport 53 -j ACCEPT
# Set rate limits for DOS attack prevention (optional)
# The rates here greatly depend on your application
-A INPUT -p tcp -m multiport --dports 80,443 -m limit --limit 250/minute --limit-burst 1000 -j ACCEPT
# Log any traffic which was sent to you
# for forwarding (optional but useful).
-A FORWARD -m limit --limit 5/min -j LOG --log-prefix "iptables_FORWARD_denied: " --log-level 7
COMMIT
For Webserver default config is like this-
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 _;
location / {
proxy_pass http://10.135.9.223:4680 ;
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;
}
With All these option I almost write down everything I guess but if anything missed pls let me tell.
So the main problem here is
when I enter url for http://web-server-ip-address it responds 504 gateway timed out
EDIT :
When I disable the firewall there is no problem.

Answer 1

Disabled the firewall and take an advantage on cloudflare if you're not familiar with those types of errors