It depends on the router. When set on repeater mode, they usually just work on wireless mode. What you need is that the router not only works as a repeater but also sets the wireless chip and the lan ports as a bridge. The only way to know would be trying. If you want to make sure without buying a switch, just connect any computer to the ethernet ports and see if you have connection to the network. If you do, then adding a switch would work just fine.