I've found that when I've encountered wifi problems with my Rokus I've normally been able to solve them by restarting the router. After the router comes back up, restart the Roku (on my separate Roku devices, it's Settings > System > System restart - should be close to that on Roku TVs) to start with a clean slate and try to reconnect.
This makes no sense to me and I don't understand why it would work, especially since other wifi devices in the house connect without issue, but it has worked for me on several occasions.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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