Implemented blocking QUIC at my firewall and found that it is now possible to get 4K 2160p60 to play but with some quirks:
- Video quality must be set to Auto. The stream starts off at 1440p60, buffers about 30 seconds of video in the background, then upshifts to 2160p60 and continues playing while still keeping a buffer of 5-10 seconds. Eventually, the buffer doesn't keep up and runs dry... the video will stall and start the 1440p to 2160p process over again and play okay again for a while.
- The Download Speed indicator does now go up to around 50Mbps on these videos when buffering. Previously capped out at ~15Mbps.
- Some videos seem more problematic than others. However, all of them appear to be getting pulled from the Google CDN in Los Angeles, CA.
- I had to disable IPv6 at the router due to packet loss upstream... this is a long standing ISP problem.
- If I manually set the stream to 2160p60 then the Roku still refuses to buffer and exhibits the skipping problem, regardless of whether traffic is being sent via QUIC(UDP) or HTTP(TCP).
- If I seek within the video after getting a successfully buffered 2160p60 stream via Auto settings, the video will not buffer and begin skipping.
- Its possible that the ISP or other provider in between myself and the Google CDN is rate limiting UDP(QUIC) traffic at around 15Mbps.
- Its possible that the ISP is traffic shaping this traffic or using something like Sandvine to downgrade 2160p60 streams (and auto mode "tricks" it).
- Google may be purposely downgrading service to Roku users.
- Roku may have a bug in its software or in the authorized YouTube app.
- Roku may have a problem with QUIC connectivity.
- I'm now on a 300Mbps plan. No change in the problem.
- I also have a new Cable modem - no change in problem.
- The TCL Roku TV is the only device in the house that exhibits this behavior on 4K content.
- Both PC and Roku playing the same 4K stream appear to be pulling from the same LA based CDN.
At any rate... disabling QUIC seems to have made it slightly better than before. I think its unlikely that the ISP is really at fault for this as the Roku is the only device that seems to have this problem with 4K content, and only on YouTube.