480 Authentication Required

“Authentication” is a fancy term for “Username and Password.” Your ISP has probably re-arranged their news server set-up and not notified their customers, which is typical for Usenet servers. Call your ISP and see what’s going on. You probably only need to enter a username/password into your news-reader software. If for some reason, you can no longer access their server, you can sign-up with Easynews, which is probably a lot better anyway.