We are currently aware of connectivity issues with one of our London datacenters. Our upstream is working to mitigate a large DDoS attack. This post will be updated as soon as we have more information to provide
2015-12-27 @ 09:11 UTC: At this time the connectivity is restored. We are still waiting for an update from our upstream, and we will update the status when we have more information.
2015-12-27 @ 09:30 UTC: The connectivity is restored. We continue to monitor the network closely. If you experience any issues, please open a support ticket.