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Your post mentions an Ethertype of 0x80 (not a typo?). It is possible that your NIC has dropped the frame before Wireshark had a chance to capture it. If the frame makes it to Wireshark it will show up in your packet list with an indicator that the protocol is unknown.

On modern computers a lot of network functionality is offloaded to a service processor on the NIC. There are still several methods to verify the transmission of the frame. Here a few hints:

  • First, verify, that non-IP traffic is captured by Wireshark (like STP, LLDP etc.).
  • Check the switch counters. This is easy with a dedicated switch with no other systems attached. Make sure that all management protocols like STP or CDP are disabled to avoid clutter.
  • If you use Ethertype 0x800, try to create a reasonable IP header with proper destination IP address.
  • Try to disable offloading for the network card.

Good luck!