Well, if the router is in sync then a red internet light usually means an authentication fault. If you've tried both test usernames and neither connect that would hint at a problem at the exchange.
The test usernames:
bt_test@startup_domain with an empty password (if possible, if not then 'password' is fine) should give you an active connection to the exchange. You won't be able to browse, but if your router shows a connection then proceed on to:
bt_test_user@**your usual connection realm** with a password of 'password' (no quotes) should connect you to our systems though again you shouldn't be able to browse.
If you haven't already please try those and update the ticket with that information (feel free to update here if you like but those results will help our faults team with the investigation).
Hope that helps,