whm cPanel tweaking for webhosting Business lightspeed server or nginx server setting

i have centos 7 own dedicated server for starting web hosting selling business. already install whm/cpanel,nginx,cloudlinux.but find some 502 bad gatway...when increse php memory not open website ..404,500 errors. also want compatible with lightspeed server . when i want run lightspeed and when i want run nginx..run for html websites,whmcs and WordPress websites smoothly and no error. check new website install no error show....also config security firewal.
please note all work done through my computer via any desk.