Unfortunately a very high packets-per-second Distributed Denial of Service attack hit an IP on the S3 server tonight. This attack wasn't large in the sense that it overwhelmed our network capacity but was large in the sense that it was a high enough number of packets that it was exhausting the web server's sockets and queues rendering sites on the IP offline.
We did identify the target of the attack and have moved them off to their own IP address - should the attack recur or adapt and we have to take action it should only affect the target site and not others on the server.
This attack was a new variant we haven't seen prior to tonight so we're using our packet captures to investigate how we could handle such an attack better and more efficiently should anything like it recur in the future.
If you have any questions about the attack do please open a support ticket. Do feel free to reference this thread.