It looks like there is a bug in the SolusVM Nginx installer which means that the php_cgi service doesn’t start on a reboot.
It seems that the installer sets the unused “spwan-fcgi” process to start, but not the “php_cgi” service that is actually used to handle SolusVM.
Luckily, this is easy enough to fix by running two commands on any of the master and slave servers which have Nginx installed:
chkconfig –add php_cgi
chkconfig php_cgi on