Roku is one of the most popular streaming devices that is used to watch movies and TV shows on your TV. Here, We will guide you to fix the "Roku not Connecting to WiFi” issue:
Check your Internet Connection Speed
Check the settings of your Router
Try to restart your Roku device.
Clear all the cache or cookies of your web browser.
Check that your Roku device is connected to the same network as your PC or laptop.
Check the settings of your DNS (Domain Name Server)
Source:-
https://techzeel.net/roku-not-connecting-to-wifi/