To avoid errors at setup is worth it to try this settings.

For production you should be good to go with standard settings (remove these)
Content > PHP > PHP.ini 

upload_max_filesize = 26M;
post_max_size = 26M;
fastcgi_connect_timeout 360;
fastcgi_send_timeout 250;
fastcgi_read_timeout 250;

Not sure if related to this configuration, but I was testing Ajenti with a suddomain.

Accessing it like sub.domain.com would download the index file. 
Accessing sub.domain.com/ajenti would open the page 

https://en.wikipedia.org/wiki/Cgroups

This enables resource limitation by user (used on CoreOS, gaining popularity among hosts) and security (Namespace section)

this should help, moving websites from cPanel https://github.com/nhnc-nginx/apache2nginx/wiki/Welcome-to-Apache2Nginx

This provides account isolation/security? 
Preventing infected websites/accounts from affecting others?