If you have a spare Wireless Modem/Router then you can use it as a basic Network Switch and/or Wireless Access Point.
In its settings, disable its DHCP server so that it doesn't allocate IP addresses to devices connected to it. Forget its RJ11 telephone connection and connect one of its LAN ports to the Philips network plug. You can then connect PCs or other network devices to either another LAN port or "wirelessly". Your *main* router will continue to allocate the IP addresses to the devices connected to the second router (which isn't now functioning as a "router", but as a network switch).