We saw also connection timeouts to DynamoDB and Kinesis from ec2 instances.
Update from AWS:
12:08 AM PST We are investigating increased network connectivity errors to instances in a single Availability Zone in the EU-CENTRAL-1 Region.
12:28 AM PST We are experiencing elevated API error rates and network connectivity errors in a single Availability Zone. We have identified the root cause and are working to resolve the issue.