We have had a couple of people have this exception in Kubernetes because the nodes can’t talk to each other. Is your setup configured so that each node can talk to each other node?
I would expect that the configuration would need to use the k8s names rather than IP addresses for all of the nodes. This is configurable in the configuration file or through env variables. More here: https://fusionauth.io/docs/v1/tech/reference/configuration/ . Look for the fusionauth-app.url setting.