title: upstream timed out (110: Connection timed out) while reading response header from upstream
body: <p>I'm new to nginx server. The problem I'm facing currently is connection timed out issue after making a call from the iOS app. The Json I'm receiving is huge hence there is a timeout logged on the server.</p>
  
  <p>Also checked with various answers posted here on stackoverflow regarding the same. But didn't help me out.</p>
  
  <p>Below is my access log and error log. Please help.</p>
  
  <p><strong>Error log</strong></p>
  
  <pre><code>upstream timed out (110: Connection timed out) while reading response header from upstream, client: xxxxxxxxxxx, server: xxxxxxxxxxx, request: "POST /api/event/gallery HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.0-fpm.sock", host: "xxxxxxxxxxx"
  </code></pre>
  
  <p><strong>Access log</strong></p>
  
  <pre><code>"POST /api/event/gallery HTTP/1.1" 504 192 "-" "mysite/2 CFNetwork/889.9 Darwin/16.7.0"
  </code></pre>
  
  <p><strong>nginx.conf</strong></p>
  
  <pre><code>user www-data;
  worker_processes auto;
  pid /run/nginx.pid;
  
  events {
      worker_connections 768;
      # multi_accept on;
  }
  
  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;
      client_max_body_size 50M;
  
      ##
      # 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_disable "msie6";
  
      # 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;
  #   }
  #}
  </code></pre>