Pods cannot communicate with each other or reach the internet until IP checksum offloading is turned off on flannel.1

[KavyaBhalodia]

Pods are unable to communicate with each other or access the internet when Flannel is running. Disabling IP checksum offloading on the flannel.1 interface using sudo ethtool -K flannel.1 tx-checksum-ip-generic off resolves the issue temporarily, but the setting does not persist after reboot.

Expected Behavior

Pods should communicate with each other and access the internet without requiring manual intervention.

Current Behavior

Pods fail to communicate, and external internet is inaccessible.

Your Environment

• Flannel version: v0.26.2
• Backend used (e.g. vxlan or udp): vxlan
• Etcd version: 3.5.15-0
• Kubernetes version (if used): v1.30.8
• Operating System and version: Ubuntu 24.04.1 LTS