nginx: 110: Connection timed out - ruby-on-rails-4

Question

Sometimes while browsing my website i am getting connection timeout error and not getting any response from server.
my error in nginx error log file is as below
*24 client timed out (110: Connection timed out) while waiting for request, client: 182.59.129.85, server: 0.0.0.0:80
After clearing the cache of the browser it works properly. but after sometime of browsing the issue comes back again.
my nginx configuration file is as below
#user nobody;
worker_processes 1;
#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;
error_log /var/log/nginx-error.log info;
#pid logs/nginx.pid;
events {
worker_connections 1024;
}
http {
passenger_root /home/ubuntu/.rvm/gems/ruby-2.0.0-p598/gems/passenger-5.0.8;
passenger_ruby /home/ubuntu/.rvm/gems/ruby-2.0.0-p598/wrappers/ruby;
include mime.types;
default_type application/octet-stream;
# limit_req_zone $binary_remote_addr zone=one:10m rate=1r/m;
#log_format main '$remote_addr - $remote_user [$time_local] "$request" '
# '$status $body_bytes_sent "$http_referer" '
# '"$http_user_agent" "$http_x_forwarded_for"';
#access_log logs/access.log main;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
# limit_req_zone $binary_remote_addr zone=one:10m rate=2r/s;
#gzip on;
server {
listen 80;
server_name localhost;
root /var/www/application/stag-NRB/current/public;
rails_env staging;
# limit_req zone=one burst=5;
#error_log /var/log/nginx/error.log;
passenger_enabled on;
client_max_body_size 10000M;
#charset koi8-r;
#access_log logs/host.access.log main;
#location / {
# root html;
#index index.html index.htm;
#}
location / {
#root /var/www/application/JCI-onsptNew/current/public;
index index.html index.htm;
# limit_req zone=one burst=2 nodelay;
}
location /download_apk {
alias /home/ubuntu;
}
#root /var/www/application/JCI-onspotNew/current/public;
#rails_env production;
#error_log /var/log/nginx/nginx_error.log warn;
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}
# proxy the PHP scripts to Apache listening on 127.0.0.1:80
#
#location ~ \.php$ {
# proxy_pass http://127.0.0.1;
#}
}