The affected AZ appears to be use1-az6. You can map "your" AZ name (us-east-1c, us-east-1d, etc.) to the actual, canonical name of the AZ in the 'Subnets' tab on the VPC console.
What makes you say use1-az6 is the culprit? I only ask because none of our workloads in az6 have experienced any issues. ....yet. We run critical workloads across 3 AZs thankfully, but still.
