OK, i just noticed something:

when clicking anywhere in the Forum (even calling it the first time), i see on my Firefox in the bottom left corner, how the page tries to "redirect"/"connect" (?) to "b.6sc.co..."
6sc.com is 6th Street Consulting (something with Sharepoint?)

And i noticed that sometimes it reacts instantly, sometimes it takes forever, with the 503-Error following prompt (though just a few minutes ago i had a 504 Gateway Timeout)

Just as a Heads up.
Might be the reason, might be not