Too Yang
heres something i found for you. i know its a bit late. you probably have it fixed by now. but maybe you are like myself, checking your post till you get an answer, if you got it fixed you would reply to you post. anyway. here it goes: ((also, they haven't made any range expanders for the N series. but you can do a few tricks to make it work with one.))
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WRE54G Does work with a WRT300N router!
First of all the computer or laptop MUST be hardwired to the router.
Second, the WRE54G MUST also be hard wired to the router.
Then, reset the WRE54GN by pressing the reset button for at least 30 seconds. (You probably get a blue and red steady light....that is fine). Hopefully, if all goes right, this will allow you to now communicate with the WRE54G. (Auto Configuration is not possible).
Now to test this: Go into your start menu and click on "Run" and type in the command "CMD"....This will give you a DOS prompt window. Now type in "Ping 192.168.1.240" (this is the preset IP Address of the WRE54G.) At this point you will get several lines of numbers and stuff...ignore everything except at the bottom where it says's "Packets: Sent = 4, Received = 4, Lost = 0 0% loss>. If this is the case then you are looking good!
Now, open a web browser and type in 192.168.1.240 and wait for the Linksys page to come up from your WRE54G.....when/if this does come up then you have won the battle!
Next, and this is also VERY IMPORTANT. In the configuration of your WRE54G the SSID MUST be the same as your router!!!! Otherwise they will not communicate with each other. Also the channels should be the same. Now click on "save setting", and it this time or shortly there after you should have 2 blue lights on your WRE54G. At this time you can unplug it and place it anywhere in your house!
Please note: at the time of all this configuration my security on my router was disabled and later also on my expander.