RSS Feed Not Working With Custom Permalinks

I am running a blog on WP 2.9. I notice that my feed works fine with default permalinks, but not at all with any form of custom permalink. (I’m using /%category%/%postname%/)

The permalinks themselves work fine, just the feed. When I load the feed URL ( https://website.com/feed) – I get “Page Not Found”

How do I overcome this?