HITL using ethernet in Ardupilot

I noticed that Ardupilot has Ethernet on CUAV-V6X, and we have used TCP/UDP connection between Simulink and Ardupilot.
Can we utilize the Ethernet for achieving Hardware-in-the-Loop (HITL) simulation, where the Flight Dynamics Model (FDM) is in Simulink and the autopilot is on CUAV-V6X? It is different from the simulation of the flight dynamics model on the hardware flight control board.
But I noticed that “TCP/UDP on hardware” in code is “SocketAPM”,and “TCP/UDP in SITL” is “SocketAPM_native”,
I can’t understand these deeper difference, Can anyone give me some suggestions on how to implement HITL with hardware network ports? Really appreciate!!!