We using SSL Full Strict and our server on GCP VM instance, on the first week everything works fine and suddenly error 521. We have checking the server using telnet and curl and our server still up and responsive. Our server IP at 220.127.116.11 . We don’t know whats wrong with this configuration.
We also check the server log at httpd/error_log and the error only show this things
script '/var/www/html/index.php' not found or unable to stat
and there are so plenty. I think this error not related with my problem.
Does we miss something? Please your help as soon as possible. Thank you.