Thanks for the post.
Can you please specify the issue you are experiencing? What do you mean by the devices aren't working? What are the steps to reproduce the issue? Have you ensured your router is broadcasting a 2.4GHz Wi-Fi network for the device to connect to? The Roku Express/Premiere is only compatible with wireless b/g/n networks on the 2.4 GHz spectrum. In addition, who is your ISP (internet service provider)?
With more detailed information, we will be able to assist you further.
@Mara1, ensure the Wi-Fi wireless mode in your router is set to b/g/n and not g/n.
I'm getting a "No Signal" message on my TV with Roku Express.
*I changed my WiFi to the b/g/n (802.11n) 2.4 gHz from 5 gHz - still doesn't work.
Is there another Roku device that is more reliable and will work on either 2.4 or 5 G?
Been troubleshooting this for two days. My previous Roku, that was discontinued, worked well. Very disappointed with this one.