Update:
here I add the log of server errors
[Wed Jun 22 15:44:08 2016] [error] [client 200.232.198.193] ModSecurity: Warning. Pattern match "POST" at REQUEST_METHOD. [file "/opt/mod_security/hg_rules.conf"] [line "148"] [id "900405"] [msg "xmlrpc POST logging"] [hostname "colemono.com"] [uri "/xmlrpc.php"] [unique_id "V2sGqGynpUQAAfVkEcAAAAA1"]
[Wed Jun 22 15:44:08 2016] [error] [client 200.232.198.193] ModSecurity: Access denied with code 406 (phase 1). Operator EQ matched 0 at REQUEST_HEADERS. [file "/opt/mod_security/hg_rules.conf"] [line "206"] [id "900331"] [msg "Joomla Com_Content SQL Injection POST"] [hostname "colemono.com"] [uri "/xmlrpc.php"] [unique_id "V2sGqGynpUQAAfVkEcAAAAA1"]
[Wed Jun 22 15:45:27 2016] [error] [client 107.167.108.81] Failed loading /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: cannot open shared object file: No such file or directory, referer: m.facebook.com/l.php?u=https%3A%2F%2Fcolemono.com%2Fasi-funciona-crash-bandicoot-en-skylanders%2F&h=qAQEA1o9T&s=1&enc=AZPY63wsEzGY-uswftS7o2D68MwDewef6cFT9eJAu3Ezo3UeVsTRF2KoE_b64G7ctf_XdeIWTALoY79RYDaWw7iX
[Wed Jun 22 15:45:28 2016] [error] [client 186.36.158.160] Failed loading /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: cannot open shared object file: No such file or directory, referer: colemono.com/asi-funciona-crash-bandicoot-en-skylanders
[Wed Jun 22 15:45:46 2016] [error] [client 200.73.66.2] Failed loading /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: cannot open shared object file: No such file or directory, referer: colemono.com/2-buenos-humble-bundles-para-hacerte-de-hartos-juegos
[Wed Jun 22 15:46:20 2016] [error] [client 201.219.233.58] Failed loading /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: /usr/php/54/usr/lib64/php/modules/ZendGuardLoader.so: cannot open shared object file: No such file or directory, referer: colemono.com/monoterapia-pilotwings-64-y-super-mario-64/?utm_medium=nt&utm_source=nt&utm_campaign=snow%20boots&utm_content=durable%20%snow%boots
I changed my site to https and from that moment I get a error 500 from the server every so often. One of the possible problems could be the Apache .htaccess file, since I modified it to force SSL.
Here I leave the file and would like to see if it is correct, thank you very much.
RewriteEngine on
<FilesMatch ".(ico|jpg|jpeg|png|gif|js|css|swf)$">
Header set Cache-Control "max-age=604800"
Header append Vary: Accept-Encoding
</FilesMatch>
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{SERVER_PORT} !^443$
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# Compress text, html, javascript, css, xml:
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript