It says on the website that it is up and I have full connection on other servers... My account isn't premium, though.
Then you should be able to join the server, although the connection is a little unstable, from my experience.
Server's back up for me. Is it still down for you? If it is, it's an error on your end. If not, I'll close this.
I think you need to restart minecraft not reset. Sometimes you need to restart then after you restart you can join other servers now.
What is the error message and what version are you running? If you try to connect using anything below 1.7 or above 1.8 it won't work.