Down time in our US East was caused by the inability to update the Backend Sets on our cloud provider's Network Load Balancers (NLBs) after a configuration update of our Kubernetes Ingress Controllers. In attempting to increase resiliency and spread of our Ingress Controller Pods on to multiple Kubernetes Nodes, we prematurely hit a limit on maximum number of "Backends" that could be added to an NLB. All new Ingress Controller Pods were scheduled on new Kubernetes Nodes, and they were not able to be added as NLB Backends due to prematurely hitting this limit. We have identified the issue as a bug in the integration between our cloud provider's managed Kubernetes and their NLBs. The bug prevents new Nodes to be added as Backends due to the Kubernetes Service adding all Nodes, instead of only adding new Nodes, as Backends on the NLB. We are currently working with our cloud provider to resolve the bug. We have mitigated the issue by significantly reducing the number of Nodes added as NLB backends. We have also added alerts to detect the issue in the future.