Hi @javierlizarralde,
I just saw that Apache is throwing a lot of error messages in the error_log file regarding the theme you are using
[Fri Apr 13 14:33:46.325043 2018] [proxy_fcgi:error] [pid 19384:tid 140133617387264] [client 217.197.240.240:43954] AH01071: Got error 'PHP message: PHP Notice: Undefined index: HTTP_USER_AGENT in /opt/bitnami/apps/joomla/htdocs/administrator/components/com_uniterevolution2/inc_php/revslider_output.class.php on line 1914\nPHP message: PHP Notice: Undefined index: HTTP_USER_AGENT in /opt/bitnami/apps/joomla/htdocs/administrator/components/com_uniterevolution2/inc_php/revslider_output.class.php on line 1914\nPHP message: PHP Notice: Undefined index: HTTP_USER_AGENT in /opt/bitnami/apps/joomla/htdocs/administrator/components/com_uniterevolution2/inc_php/revslider_output.class.php on line 1914\nPHP message: PHP Notice: Undefined index: HTTP_USER_AGENT in /opt/bitnami/apps/joomla/htdocs/administrator/components/com_uniterevolution2/inc_php/revslider_output.class.php on line 1914\nPHP message: PHP Notice: Undefined index: HTTP_USER_AGENT in /opt/bitnami/apps/joomla/htdocs/administrator/components/com_uniterevolution2/inc_php/revslider_output.class.php on line 1914\nPHP message: PHP Notice: Undefined index: HTTP_REFERER in /opt/bitnami/apps/joomla/htdocs/templates/lt_agriculture/index.php on line 12\nPHP message: PHP Notice: Undefined index: HTTP_REFERER in /opt/bitnami/apps/joomla/htdocs/templates/lt_agriculture/index.php on line 27\n'
...
[Fri Apr 13 14:33:51.822346 2018] [proxy_fcgi:error] [pid 29607:tid 140133927917312] [client 217.197.240.240:45948] AH01071: Got error 'PHP message: PHP Warning: require_once(/opt/bitnami/apps/joomla/htdocs/libraries/joomla/document/html/renderer/head.php): failed to open stream: No such file or directory in /opt/bitnami/apps/joomla/htdocs/templates/lt_agriculture/error.php on line 42\nPHP message: PHP Fatal error: require_once(): Failed opening required '/opt/bitnami/apps/joomla/htdocs/libraries/joomla/document/html/renderer/head.php' (include_path='.:/opt/bitnami/php/lib/php') in /opt/bitnami/apps/joomla/htdocs/templates/lt_agriculture/error.php on line 42\n'
...
I suggest you ask the developers of the theme to have more information about these issues.
Regarding the favicon, I only saw 2 entries in the log (related with pageSpeed), could you please disable it and see if the issue disappears?
https://docs.bitnami.com/google/components/pagespeed/#how-to-disable-pagespeed
Thanks.