Before this goes any further I wanted to make sure you know this method (if you found a working solution) would only allow you to use one connection at a time and is not how "Ethernet Switches" are typically made. Ethernet switches don't just rapidly switch from one wire to the next so an Internet connection is shared. Switches take multiple inputs, tag the outgoing packets and re-route tagged incoming packets to where the request originated. Don't be offended if you already knew all of that, just didn't want you to get the wrong idea.