If you go to planet.wordpress.org (also called the WordPress Blog)
It's at the top of every page on this website wordpress.org when you click on "Blog".
Once you are there, try clicking the nav link at the top for "Forum". (AKA this support forum).
It doesn't work. You get a 404. It tries to send you to planet.wordpress.org/support/ instead of just wordpress.org/support/