I am having the same issue. I have 2 Roku Express that stopped working on the same day. My Roku Ultra is working fine. I have restarted the router multiple times. Put the Roku back to factory settings and I still can’t connect to WiFi. The Software version is 10.0.0 build 4209. Model 3930x
Jkornacki , if you have Comcast/Xfinity or Cox as your ISP go into your router settings and change the wireless mode from g/n to b/g/n. It has also been reported that if you have Xfinity you can use their app to forget the Roku devices and then reconnect them from Settings->Network on your Roku.
Thank you for this suggestion. I called Xfinity and they were able to adjust my router settings and now both Rokus are up and running.
This worked for me. Thanks!
