Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
My "new & improved" Express shows error NW-6-503 when I start the Netflix client, but Amazon Prime and Hulu work fine; also, Netflix works fine on my old Express. Apparently Roku is getting away with not supporting their products, so this is my only option for help.
A few issues: The site is not in English, and there is no mention of Roku. However, the author says that it's a common Netflix error for people watching Netflix in a browser. I also found mention of a nw-6-504 but that was on a Xbox. There are a bunch of these nw- error codes listed on Netflix's site, but I couldn't find that specific one.