To use the Jetpack plugin, you’ll indeed need to link your site with the WordPress.com service, as many of our core features (like Photon, Stats, and Protect) make use of the WordPress.com cloud.
That connection between your site and WordPress.com happens via a file on your WordPress installation, named XML-RPC.
However, if for any reason that file can’t be accessed, you’ll receive the error you reported in your post.
Access to this file may be blocked for different reasons:
- Your site has to be accessible to the public (and consequently to WordPress.com). Maintenance plugins or membership plugins that restrict access to your site may also restrict access to that XML-RPC file.
- You may be using a security plugin to block access to the file. If so, you’ll need to configure it to allow incoming and outgoing connections to /xmlrpc.php.
- If you do not use such plugin, you’ll want to contact your hosting provider and ask them if they currently block access to your site’s XML-RPC file.
I hope this clarifies things a bit. If that doesn’t seem to help with your site, could you post your site URL here, so I can have a look?
If you want it to remain private, you can also contact us via this contact form:
https://jetpack.com/contact-support/