Answer
Port 10250 belongs to Kubelet (the Kubernetes node agent responsible for managing workloads on cluster nodes) — this connection isn't really meant to reach a service running on your database server itself, and a connection-refused error here points to a firewall blocking that port, most likely on the Middle Tier server rather than something that needs configuring on the database server. Check the Middle Tier server's own firewall rules for port 10250 rather than trying to open anything on the database host.