Sorry cant make it any clearer
Working internet on 3 Pc's connected direct to router, 2 by ethernet and 1 by wireless and homeplug has a ps3 and Pc connected as soon as either of the device connected to the homeplug is switched on the first 3 lose there internet connection and the Ps3 and Pc then get a internet connection (i cant even log onto the router config page with the first 3 Pc's).
This setup works fine with my netgear router.

Does sound like an IP conflict problem