the hub is correctly sensing it to be 10mbs.

It is possible that the hub is the problem. There are reports of 10/100 hubs that don't properly work with car player, despite claiming that the port is working at 10. I don't know if this is the hub's fault or the player's fault.

Or maybe what you need to do is throttle your PC's ethernet card back to 10 and that might make it work?