Livewire has no network access

Device 1 is plugged into one port of a WRT54g router.  Device 2 is connected to my laptop.  The PLC link LEDs on both de devices are blinking after I synced the devices by pressing the buttons on them.  But alas, the wired connection has no network access because “Local Area Connection doesn’t have a valid IP configuration”.    The wireless connection works fine.  If I remove the network cable from device 2 and plug it into an available port on device 1, or the router, the local area connection is successfully established showing me a wired and a wireless connection to the internetin Network and Sharing Center .  Disabling the wireless adapter and powercycling everything did not help.  Maybe you have some insight?  Thanks!

There are few reasons that this could be happening.  How far away are the two products?  Could this be going through big circuit breakers? 

Hi PC SoCal, the two devices are not close together.  One is in the main house, the other one in a cottage on my property.  The reason for pursuing this solution is a weak wireless signal to the cottage.