Support

Does your configuration.php file have a non-empty $live_site line?

The problem that you had was that you had simultaneously a $live_site without www and told the .htaccess Maker to redirect non-www to www. This created a redirection loop, exactly was you have been warned about in Admin Tools' interface. When you were trying other access santagatarestaurant.it the .htaccess file generated by Admin Tools followed your instructions to redirect it to www.santagatarestaurant.it. However, when you tried to access www.santagatarestaurant.it Joomla was following your instructions in the configuration.php to redirect back to santagatarestaurant.it.

The correct solution is to start by emptying $live_site, setting that line in configuration.php to

public $live_site = '';

You only need to set $live_site if you are on a badly configured server behind a reverse proxy which results in the HTTP Host header not being forwarded to or honored by your web server. 99.99% of servers out there do NOT have this kind of misconfiguration, which is why the recommended setting for $live_site is an empty string, telling Joomla to figure it out from the HTTP Host header.

Regarding having problems when enabling Admin Tools, we have already documented that you can start with the minimum number of settings enabled, then start enabling one thing at a time to see what is supported by your server and what makes sense on your site.