My Roku says the wireless connection is great but the apps don't work because it's not connected to the network. I restart my device and then restarted the router but nothing changed. I looked at other posts on here and a lot of them talked about the 9.3 update and this same problem. My device says it's still on version 9.2.0 and it checked for updates earlier this afternoon. I tried to manually check for the update but it won't allow me to since it won't connect to network.
I did the things you suggested and neither of those things worked so I started looking more into my own internet. This is where the problem was - I had to flush the DNS. Roku is now working properly but it still hasn't detected the update. However, I'm not going to mess with it anymore since everything seems to be okay and I'll just let it do it's own thing!