Activating the Jetpack
What to do if the following error appears during Jetpack installation:
Your website needs to be publicly accessible to use Jetpack: site_inaccessible
Error Details: The Jetpack server was unable to communicate with your site [HTTP 403]. Ask your web host if they allow connections from WordPress.com.
To activate Jetpack, the xmlrpc.php file must be accessible. To do this, add the following rule to your .htaccess file:
<Files xmlrpc.php> Allow from all </Files>