Cilium network policies (CNPs) enhance Kubernetes by extending L3/L4 controls to the application layer (L7), offering advanced networking capabilities that can also introduce new connectivity challenges, especially in large environments. These challenges often arise from differences in how Kubernetes and Cilium interpret concepts like label scoping and IP-based rules, impacting areas such as cross-cluster communication, egress rules, CIDR-based L3 policies, and namespace isolation. Misconfigurations can lead to unintended traffic blocking or allowance, requiring careful policy structuring and understanding of Cilium's unique handling of cluster entities and security identities. To address these issues, Cilium users must navigate policy settings such as the policy-default-local-cluster and use appropriate selectors like endpoints-based policies for cross-cluster traffic or entity-based policies for internal traffic, ensuring correct implementation for desired connectivity outcomes. Awareness of these differences and proper monitoring using tools like Hubble can help in diagnosing and resolving common misconfigurations, ultimately leading to more reliable and secure network policies.