Within minutes returned Error 404, and a few minutes later returned to normal again.

I’m having a problem where one of my websites often experience Error 404. But at other times it also runs normally. Within minutes returned Error 404, and a few minutes later returned to normal again. This problem occurs again even though the cache has been cleared. Even switching to another computer.

What happened to my website, and how can I overcome it?

Note: Using PHP 7.3, Wordpress, and runs on Centos7 VM.

https://forum.openlitespeed.org/ if you can’t find it.