This also meant that the Roku would suffer greatly, causing unreasonable buffering for shows I wanted to watch; sometimes they wouldn't play at all

Incessant buffering will drive you crazy.

No stutter, 4K quality, no noticeable buffering

ABC/NBC/CW stream very well, with very limited interruption or excess buffering.

Fast speed, no buffering, and easy to use interface.

This Roku is very fast compared to the older Roku 2.I use a wired connection and suffer only occasional buffering (probably due to internet congestion); the streaming of 4K work well with a gorgeous picture

Except for arriving in a brown box instead of a retail box, and having an annoying "B Stock" sticker on the back that was hard to get off, I have no complaints with the refurb unit