We check this website, now tu-chemnitz.de is up and dont blocked for our system and other users of the Internet.
So, answer to question: Is tu-chemnitz Down Right Now? - NO! tu-chemnitz is up!
If you have problem with access to site tu-chemnitz, and domain tu-chemnitz.de is not avalible.
Clear browser cache and/or try other web browser
(Chrome, Firefox or Safari).