Extend wifi network with Express not working
I have an Airport Extremem base station already, and I'm trying to extend the wifi with an Airport Express placed on the far end of my house. The set up seemed to go okay, but after the Express reboots after set up, it briefly comes up with green LED on the unit itself and on my Airport Utility on my iPhone then the status is amber color with 1 status message that says:
"This AirPort base station was unable to extend the wireless network. Make sure the wireless network you're trying to extend was set up and is working correctly, that you entered a matching wireless network password into this device, and that this device is in range of the wireless network."
1. My existing wifi network is working fine. I'm just trying to boost the signal on the far end of my house.
2. My network password is correct.
3. The device is definitely in range of the wireless network because it's at the same spot where my TV is, and the TV gets wireless connect to my network (albeit very low signal strength).
Help!
MacBook, Mac OS X (10.5.5)