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)

I am pretty sure now that this is a problem at Youtube and not anything to do with VMix or the local PC.
This problem is also reported by OBS users and there is a thread on the Youtube support forum about it (see here: https://support.google.c...=4717194706976095421-NC)
There doesn't seem to be any way to contact Youtube/Google about this.

We have found a temporary fix which is to setup alternative stream settings using "Custom RTMP" to b.rtmp.youtube.com (using the same streamkey as you use normally) and also another to x.rtmp.youtube.com (using the same streamkey). When the stream button starts flashing orange, click the cog next to the stream button and change to one of the other stream settings. This sends the stream to a different ingest server at youtube. Keep trying different servers till you get one that works. That's the only way I have found to get round it at the moment.

That's an interesting result. Maybe I am wrong then. We just have the one computer and no alternative networks to try so I am limited in what I can test.

I have very low CPU/GPU usage. About 9% each.
The strange thing for me is this was working perfectly before 4 weeks ago and nothing has changed that I know of.
Also, I can do a video streaming test using Speedtest and there is no problem with my network upload speed - it just seems to be a problem when going to Youtube.

In my case the GPU Mem was very high and I reduced it by removing resources.
However, it was not the solution as you say.

Today's broadcast made me sick.
No matter what setting I make, whether vmix or obs, the same problem persists. I'm using Windows 10 and I guess it's with the new update. USB ethernet did not provide a solution either. I'm currently working on it by outputting externally via Decklink and sending the broadcast via WebPresenter. I also changed the internet and tried posting to other platforms. The result did not change. I even tried sending it to the main url via vmix and to the backup url via obs. The source of the problem is not vmix, but I am waiting for help with the solution.

Yes

Can you send SRT to youtube? I can't find a way to do anything other than RTMP.

Yes, it is happening on a laptop and a desktop, 2 totally different machines with wildly different components. Only common things are vMix and Windows 10.There was a Windows update in the last few weeks; there's always a "recent" update. But I'm at a loss to debug this. It happens at random times.

Yesterday I did a 4h stream to another rtmp server, so not YT. I had zero issue. Have you checked that network throttling is disabled?
How?
cmd: netsh interface tcp show global
Under results, look for "Receive Window Auto-Tuning Level" If it is set to normal, it means it is enabled.

How to disabled Window Auto Tuning?
cmd: netsh int tcp set global autotuninglevel=disabled press Enter
An Ok. message will appear.
Reboot your computer and router.

I hope that helps.