I am getting the exact same message, but the RSS feed has never worked.
My web host has asked if the plugin uses a specific non standard port? If so, we can check to ensure it is not a blocked port within the server firewall.
Does anyone know the answer?
Thanks
Fantastic, thanks Mark and Nicandia, I have been hunting for a solution that works and this is it!
One small point – is it better to copy the whole comments.php file into a child template and amend it there, to prevent WordPress updates setting it back again?
Thanks for your help, really appreciated.