RSS Feed doesn't appear to be working

I have a Drupal site, most of the content of which is hidden from unauthenticated users.

I am using the Frontpage module to display a different frontpage for unauthorised users.

Once logged in, users can create content that is publiched to the authenticated users frontpage automatically. The RSS feed looks at this authenticated list of published items on front page items.

I want to be able to make that RSS feed available to unathorised users. There is other content on the site that should remain blocked, and it is only items on that authorised users front page that I want to make available through the RSS feed for unauthorised users.

I have installed the RSS Permissions module and made the feeds available to unauthorised users. But visiting https://www.swim-club.org/gsc/?q=rss.xml just shows the default Drupal unauthorised access page. It works fine if I am logged in, but doesn't work if not.

What am I missing ?

Thanks