How to disable TX checksum offloading

Checksum offloading on a network card may cause issues in some setups, including on VMware instances and in Cilium. If you encounter such issues, take the following steps:

1. Disable TX checksum offloading by running the following commands:

   cat <<EOF | sudo tee /etc/systemd/system/disable-checksum.service
   [Unit]
   Description=Disable TX Checksum Offload
   Before=rke2-service.service
   Wants=network-online.target
   After=network-online.target
   
   [Service]
   Type=oneshot
   ExecStart=/bin/bash -c "INTERFACE=$(awk '$2 == 00000000 { print $1; exit }' /proc/net/route); ethtool -K $INTERFACE tx-checksum-ip-generic off || ethtool -K cilium_host tx-checksum-ip-generic off || true"
   RemainAfterExit=true
   
   [Install]
   WantedBy=multi-user.target
   EOF
   sudo systemctl enable disable-checksum

2. Restart the affected instance by taking the steps described in Starting and shutting down a node.