Debug BackendConnectionErrors from Kubernetes Service LoadBalancer sesrvice
My solution to this problem was to rework my Services. The setup in my question had one K8s Service with ~10 ports. I reworked the setup to use one port per Service. The problem went away. I don't know why though. This makes me suspect something on the nodes themselves or some complexity in routing connections to the correct node port. I'm cautious of exposing too many ports again because of this.