Huge apologies everyone for today's downtime! One of our IP addresses had suddenly died (still clearing this up with our server provider).
Please let us know if you would like to cancel any CWs or duels that were started before the server went offline.
EDIT: Apparently there was a massive DDoS attack (over 6 Gb/s!) and one of our IP addresses was automatically blocked. The provider has added more protection and everything should be back to normal now.