The buffering issues might not be due to the Roku streaming device, but maybe due to your home network. For this #rokubufferingissue, make sure to check the internet speed. Refer to the steps below to fix buffering issues on Roku.
https://rokuolink.com/roku-buffering-issues/

Resolve buffering issue with Roku streaming stick via roku.com/link
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Resolve buffering issue with Roku streaming stick via roku.com/link

Is Roku buffering issue all the time? It’s time to upgrade your router or switch to a new Roku streaming stick. But before that, you can try these remedies.