Three days ago we came home from work to find that all 4 of our streaming sticks aren't connected and no matter what we do they won't connect, even the TV that is mounted on the wall directly over the router. All of them show an "excellent" signal and Xfinity says there's no problem with our internet but when trying to reconnect we get the red X and no connection. One TV here or there will randomly connect and start working just to stop again later. All other devices are working in all rooms (desktop, laptop, tablet, phones). I was able on one of the TVs to connect to the mobile hotspot on my phone but not to my internet.
This all happened with the OS 10 update. Our streaming sticks are less than 3 months old and have worked perfectly from day one, never once losing connection or having a slow connection.
We have restarted the Roku, restarted the modem, rebooted the system, reset the network and tried to log back in, unplugged and replugged for different lengths of time. There's really nothing we haven't tried. On one of them we even did a factory reset which is a disaster because now the remote won't work and we can't do anything without a connection and it still won't connect.
We have now gone 3 days without TV and are frustrated enough and are about ready to throw them all the trash and call it a loss.
Thankfully I was finally able to fix the problem and get reconnected.
I changed my router from auto channel settings to 11 for 2.4 GHz and 153 for 5 GHz. Then I unplugged the router, modem and all 4 Roku sticks for 10 minutes. I plugged the router and modem back in for 5-10 minutes. Then I reconnected the Roku sticks and logged back into the network and they all worked.
Good to hear you are back up and running, and thank you for posting the fix that worked for you. You should find you have far fewer problems now that you have manually set your channels. Probably nothing a simple router restart or a System Restart from within the Roku devices can't fix from here on.