If you are occurred an error  when you configured reverse proxy to another web server, need to increasing value of proxy_read_timeout in NGINX configuration file.

Open your nginx.conf file, then add below line at specific section,

proxy_read_timeout 300;

server {
    listen       80;
    server_name  domainname.com;
        ...
location / {
            proxy_pass   http://192.168.0.1:80;
            proxy_read_timeout 300;
           ...
           }
        ...
        }


Another options is increease  fastcgi_read_timeout,

fastcgi_read_timeout 300;

or update in php.ini configuration file.

max_execution_time = 30