It is very possible that placing the Express in the basement has moved it outside the useful range of the Wi-Fi signal coming from the Actiontec wireless router.
You will want to place the Express within a 25+ dB range of the Actiontec. You can determing this by using your MacBook Pro to make Signal-to-Noise Ratio (SNR) measurements.
To do so, you will use the built-in OS X Wireless Diagnostics, as follows:
- Option-click on the AirPort icon on the OS X menu bar.
- Select "Open Wireless Diagnostics..."
- Enter your Mac's Administrator credentials in the next window.
- On the Wireless Diagnostics window DO NOT click on "Continue." Instead, go to the diagnostic's menu bar, and then, select Window > Utilities
- Start the test with the laptop near the wireless router. Note the values for RSSI and Noise. They should both be negative and measured in dBm.
- Now take the laptop to the other locations that you want to access the Internet in your home. Different rooms, different floors, etc. Again, note these same two values at each of these locations.
- When you have finished collecting the data, you will want to enter them into the following formula for Signal-to-Noise Ratio (SNR). SNR = RSSI - Noise. For example, if your get the following readings: RSSI = -61 dBm and Noise = -84 dBm, SNR = (-61) - (-84) = 23 db
To get decent wireless bandwidth performance at a location you will want the SNR value to be 25+ dB.
