I'm having a strange problem for the last few weeks livestreaming a church service to youtube and wondering if anyone has any advice on things I could try.

This setup has worked perfectly for a couple of years. We use a 4G router for internet connection which is showing a good speed of about 20mbps upload using Speedtest (both the basic version and the video streaming test version). There is no wired internet at the venue to test with. We transmit a 720P/30 data stream set to 3.5mbps.

Before our church service starts we transmit a Powerpoint intro sequence which is static images changing every few seconds (so, not much video data rate). The livestream works fine. CPU and GPU usage is low (about 10%).

The last few weeks, very soon after the service starts at 10.30am and we go to a live picture of the service leader, the Stream button starts flashing orange. The log (checked later) is showing "real-time buffer too full or near too full ". The youtube video (checked later) is watchable but appears to be half the usual frame rate (so every other frame getting dropped). Speedtest is still fine at this point. CPU/GPU is still fine. Stopping the stream momentarily and restarting it fixes the problem for about 60 seconds. Stopping the stream and switching to the backup youtube ingest server (b.rtmp.youtube.com) fixes the problem for the whole remainder of the stream.

So thinking it was a congestion problem at Youtube, the next week I started off the stream to b.rtmp.youtube.com, but had exactly the same issue at 10.30. Switching back to a.rtmp.youtube.com fixed the problem for the whole rest of the stream.

The only thing that's changed is I guess Windows may have done an update and broken something on the streaming laptop, but it looks more like a problem at Youtube than at my end. I am a bit confused what to try next.


(Edited to add: having posted this I now find some other posts with others having exactly this problem and it does appear to be specific to Youtube)