We've had a bit of a nightmare over the last week or so. We've been constantly battling with obscure DDoS methods, locking down our servers with new filters each time. As a result of these changes, ICMP has been blocked completely (which means you can't do trace routes nor MTRs to the server, however, this was for the best), and a bunch of other filters have been added to protect SSH ports, game server ports, and all other unused ports have been dropped. Hopefully this should mean that after today (where we've applied filters to drop BACnet UDP packets, which were causing problems) DDoS attacks either become a lot rarer, or possibly even non-existent on our nodes.
We've never heard of a BACnet UDP attack, and it's likely you haven't either; but essentially it's an explot where attackers can make use of the BACnet port (47808), even if it isn't open, and use this to DDoS a node. This shouldn't have happened with Path.net's protection, however, their team is looking into it and dropping the protocol by the time we wrote this message.
Again, we'd like to thank you for your patience over this hugely annoying period. We will continue to monitor the situation, and implement new filters when things go wrong - let's hope they don't!