My Roku Premiere worked great since mid-May; however lately, many of the channels, especially the Spectrum channel are very low quality, pixelated, and show "Buffering..." often. I've rebooted the unit several times, checked the wireless network connection and it's fine (reset it twice as well), and checked with Spectrum Internet, and it's working normally as well. Anything else I can do, besides returning the unit and going with Amazon Fire TV??
Wish I could help. I’m having the same problem, which seems to be getting worse.
See if this helps with your wifi buffering problems:
If this still doesn't work, try pulling the power plug on your Roku for a minute or so then plugging it back in. When it's finished restarting, try to reconnect the network again.