My money's also on a NIC checksum/segmentation offloading bug. Even though it apparently isn't controllable via the exposed parameters, the card does have these

My money's also on a NIC checksum/segmentation offloading bug. Even though it apparently isn't controllable via the exposed parameters, the card does have these features. "TCP/UDP checksum and segmentation offload (IPv4 and IPv6)" on the spec sheet https://www-ssl.intel.com/content/dam/doc/product-brief/82579-gbe-controller-brief.pdf https://www-ssl.intel.com/content/dam/doc/product-brief/8257...