Historical field reports associated some host-adapter offload settings with DECnet, TCP/IP, or System Communications Services (SCS) problems.  A physical Intel I226-V/Npcap test reproduced Avanti's host-originated IPv4, TCP, and UDP checksum-repair counts with the corresponding transmit offloads enabled; disabling each transmit setting alone removed its matching count.  The tested TCP and UDP file transfers completed with matching hashes in every state.  This does not establish that an offload setting caused the historical communications symptoms, and results may differ by adapter and driver.

If one of the following symptoms is repeatable, record the Windows adapter and driver, packet backend, traffic direction, protocol, guest NIC, and current offload settings before changing anything:

•Unable to establish communications to the Avanti NIC.

•Communications with Avanti are unstable (time outs, packet loss)

•Cluster communications are unstable (SCS cluster time outs, packet loss)

As a controlled diagnostic, disable one applicable transmit checksum-offload setting at a time in the Windows adapter's Advanced properties and repeat the same workload.  Do not infer a cause from disabling several features together, and do not attribute Large Send Offload or receive-only features to checksum repair without separate evidence.  Restore every former value after the test unless the isolated change reproducibly corrects the recorded case.