It looks like several things happened to make this situation fairly bad.
First, our XB1 monitoring got screwed up during the data center move. So it appears there were several DDoS attacks that none of the team were aware of.
Second, the DDoS attacks were so large that our ISP decided to block all traffic to the Xbox district for a period of time.
We're working on the situation now with our ISP to get better notifications from them when they block IPs.
And we're rebuilding our monitoring for XB1.