First thing to check is compatibility issue.
Linksys WRE54G Wireless-G Range Expander is compatible with Wireless-G networks only.
WRE54G is NOT COMPATIBLE with Wireless-N networks.
Here is a link to the setup wizard.
http://homesupport.cisco.com/en-us/wireless/lbc/WRE54G (can use this for common issues also)
If the Link LED on the Wireless Range Expander lights up red, this indicates that there is no wireless connection between the Linksys Wireless Range Expander and the Wireless Router or Access Point. To fix this, you must be using the latest firmware for your router or access point.
NOTE: Make sure the wireless router or access point is already properly configured and there should be active wireless connection to all wireless computers/clients.
1. To check the firmware version on a Linksys wireless router or access point, click here.
2. To verify if there is newer firmware go to
http://www.linksysbycisco.com and click on Support
3. Select your model number and click on "Get Downloads"
5. Select your version number
6. Under Downloads & Drivers you should see the latest firmware for your product, download it to your desktop if it's newer then what your router has.
7. To update your router's firmware, click here. To update your access point's firmware, click here.
8. The WRE54G and the wireless router or access point needs to have the same wireless settings in order for them to connect.
a. To get the current wireless settings of your wireless router, click here.
b. To get the current wireless settings of your wireless access point, click here
NOTE: If you are using a non-Linksys wireless router or access point, contact the manufacturer to get the wireless settings.
Configuring the Linksys Wireless Range Expander
Step 1:
Access the range expander’s web-based setup page. For instructions, click here.
Step 2:
When the range expander’s web-based setup page opens, enter the current wireless settings of your wireless router or access point such as SSID (Wireless Network Name), Channel, and Wireless Security.