My customer have an office small office with just a wifi router. He use this router for internet connectivity and file transfer operations between the desktops.

Recently the file transfer activity between desktop (all osx based) is increased a lot so he bought a switch (no connected to the router, too far away) for transfer the file over the cable instead over the wifi.

Problem: How to bind the file sharing service just to the Ethernet interface and exclude the wifi interface ? (actually the service binds to the wifi automatically and there are no options about the interface binding)