It appears they are performing emergency maintenance on several routers. Here is a snippet from their status page:
During the above-mentioned time frame, we will be carrying out urgent maintenance work on the access router fsn1-dc13-ex9k2, fsn1-dc13-ex9k1, fsn1-dc11-ex9k2, fsn1-dc11-ex9k1, and the connected ToR switches. During this work, network traffic will be interrupted, meaning that affected customer systems will not be accessible during this time. This also affects vSwitches for Dedicated Root Servers. Private Switches and Custom Solutions are excluded from the maintenance, unless explicitly stated.