how to switch from mpm_event_module to mpm_prefork

Hi,
I´ve got to solve this..

Installed 3 servers with  CWP version: 0.9.8.259 on Centos 6.9 2  unsing Apache 2.4.26 each server has 2 cores & 8 gb RAM (all the same)

Their main task: just webserver 1 site, mysql is installed in another server and I´m using CloudFlares CDN and a LoadBalancer.. all works fine.. but im having this issue...

Initially I´ve left the three servers with default configs, so each server only has apache and mpm_envent_module with default config..

Suddenly apache stop to work, the cpu usage drops near to 0% (when running normaly they are between 10-15% cpu use).. this happened on differnt times on the three servers..

so I stop apache service..(takes a minute or two to stop) and when try to start it just stands there... so I have no other choice to reboot server..and then return to normal..  all this from from ssh.. not from cwp.
 
Checking apache error logs. I´ve spoted this "[mpm_event:error][pidxxxx]Script timeout before returning headers: index.php
[mpm_event:error]AH00484 server Reached MaxRequestsWorkers setting, Consider raising the MaxRequestsWorkes setting]

so, I´ve uncoment '#' at the Include/conf/extra/httpd-mpm.conf at httpd.conf and then edited the httpd-mpm.conf.. there I´ve set this values.. ThreadsPerChild 50 and MaxRequestsWorkers 800 (default was 400)

restarted apache.. hoping this might solve the issue.. but after a few hours got the same behaviour..

so, in only one of the servers I´ve installed Ngnix and apache... hoping this solves it..

Installation went ok.. but now this server shows me a Bad Gateway (502) screen after 1 hour of running... and I have to reboot it..

Reading on the web mentioned that this could be a bug..of the mpm_event.. so decide to try with mpm_prefork.. but I´m unable to find a way to enable it? how can I do that? I´m just trying this only on one server, the one who has ngnix .. and if it fixes the issue then I´ll update the others..

Can anyone assit? or give me a hint regarding my issue?


thanks!







if I try to access to the webpage located at the server I just got a blank page..eventually a cloudflares showsme that my server is down...