Getting 502 Bad Gateway error on nginx/node/mongodb website. (111: Unknown error)

I built an website using nodejs, nginx and mongodb. It is hosted on AWS EC2 and uses Route 53. We set up the SSL certificate using Certbot.

It was working fine till about a month ago. Now it gives 502 Bad Gateway on https and 404 Not Found on http. It works on port 5005 but port checker shows it is closed.

Error Log

2022/07/08 04:39:48 [error] 251318#251318: *51396 connect() failed (111: Unknown error) while connecting to upstream, client: 209.141.35.128, server: alltimeschool.com, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:5005/", host: "alltimeschool.com"

2022/07/08 04:39:49 [error] 251318#251318: *51395 connect() failed (111: Unknown error) while connecting to upstream, client: 209.141.35.128, server: alltimeschool.com, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:5005/favicon.ico", host: "15.206.123.65"

2022/07/08 04:39:49 [error] 251318#251318: *51396 connect() failed (111: Unknown error) while connecting to upstream, client: 209.141.35.128, server: alltimeschool.com, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:5005/favicon.ico", host: "alltimeschool.com"

Nginx configuration file:

    user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
    worker_connections 768;
    # multi_accept on;
}

http {

    ##
    # Basic Settings
    ##

    sendfile on;
    tcp_nopush on;
    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 TLSv1.3; # 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/*;
}


#mail {
#   # See sample authentication script at:
#   # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript
#
#   # auth_http localhost/auth.php;
#   # pop3_capabilities "TOP" "USER";
#   # imap_capabilities "IMAP4rev1" "UIDPLUS";
#
#   server {
#       listen     localhost:110;
#       protocol   pop3;
#       proxy      on;
#   }
#
#   server {
#       listen     localhost:143;
#       protocol   imap;
#       proxy      on;
#   }
#}