Help & troubleshooting for network issues, including connecting your device to your home Wi-Fi network, connecting to public networks, troubleshooting wireless issues & ethernet connections, and optimizing streaming performance.
-Have you ensured your router is broadcasting a 2.4GHz Wi-Fi network for the device to connect to? The Roku Express is only compatible with wireless b/g/n networks on the 2.4 GHz spectrum. - Have you tried changing the wireless broadcast channel on the router to see if this will allow your device to connect?
If those things still aren't helping, feel free to send me a PM with your Roku account email address and the serial number of your Roku from Settings>System>About and I'll be able to assist you further from there.