It is very common to see a 504 Gateway Time-out using Nginx webserver. This timeout error is generated often by a number of reasons on the backend connection that is serving content. To fix it, you will have to figure out what configuration are you using.

For Nginx + FastCGI (php-fpm), you should try to tweak nginx configuration in this way-:

Try raising max_execution_time setting in php.ini file (CentOS path is /etc/php.ini) or (Debian path is /etc/php5/fpm/php.ini):

max_execution_time = 300

But, you should also change set request_terminate_timeout parameter (commented by default) at www.conf file from PHP-FPM (CentOS path is /etc/php-fpm.d/www.conf) or (Debian path is : /etc/php5/fpm/pool.d/www.conf)

Then set the variable to the same value as max_execution_time:

request_terminate_timeout = 300

Now let’s add fastcgi_read_timeout variable inside our Nginx virtual host configuration:

      location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/var/run/php5-fpm.sock;
        fastcgi_read_timeout 300;
     }

In another cases we have the control of the timeout into the Nginx Server configuration like this into nginx.conf

        ## Timeouts ##
        # Timeout for reading of the client body
        client_body_timeout   300;
        # Timeout for reading the client header
        client_header_timeout 300;
        # Timeout for keep-alive 
        keepalive_timeout     300;
        # Timeout for response request 
        send_timeout          300;
        ## Timeouts ##

Then restart nginx:

service nginx reload

For Nginx as Proxy for Apache web server, this is what you have to try:

Add this variables to nginx.conf file:

proxy_connect_timeout       600;
proxy_send_timeout          600;
proxy_read_timeout          600;
send_timeout                600;

Then restart nginx:

service nginx reload

1. https://www.scalescale.com/tips/nginx/504-gateway-time-out-using-nginx/