Update: I just had a go at this Sunday morning 9am...and no buffering at all on VDSL. The video streamed perfectly for 10 minutes. Well done. So it very much looks like local congestion in my area. The last mile. 

I'll leave the post here more as evidence of my own cynicism combined with observations. Hopefully I've learned something here. :-)  

******************************

I moved to Telecom's ADSL a while back and was pretty happy. I could watch streaming video with barely a burp or glitch. So we have gradually increased our monthly data quota up to 500GB. Oddly enough, as we increase our cap, the reliability of the capability to stream video has declined. 

My wife and I have been watching some shows from the UK via the ITV Player. On the ADSL 2+ in the evening on the weekend (probably peak-ish time) we would watch about a minute's worth of content, then wait about 15 seconds and then get a minute...and then wait....then maybe 30 secs....and wait a minute...and so on. Barely watch-able if you're really patient. 

Yesterday, we upgraded to the VDSL service. The flow of video from the same source improved slightly (I think...or maybe not), but still conformed to the same overall pattern of barely-watchable. This is on a nominally 40mbps downlink.

I hear you say: "But it's coming from the UK! The global network state will be the main factor!"

That's what I thought, too.

Until I wifi-connected the PC to my LTE phone and watched an entire 90 minute episode with only one or two very brief glitches. Hmmm..... so global network state would appear to be irrelevant. The data throttling (be it coincidental congestion in the last mile or active network "management" - no idea) is going on MUCH closer to home.

Last night I tried it via a different phone on 3G (nominally 14mbps - same as my old ADSL2+) and it buffered a bit more than on LTE , but the stream was easily watchable and it flowed very well. 

So what can I (provisionally!!!) conclude from this? Very broadly, it FEELS like the higher your landline data cap, the lower your effective throughput rate over time for the purpose of streaming video. This is indicated by the HUGE improvement one sees when doing exactly the same thing from the same source in the same time of day via much more expensive mobile data....even when the mobile data is nominally the same throughput (14mbps) as the land-line broadband. 

I can see why this would be the case. Probably less congestion on the 3G. Higher priority given to the higher value data...plus whatever else. 

Edited: If the problem isn't local congestion (though it probably is) I'd wonder what price I might have to pay to get a 500GB cap that is actually usable for the intended purpose? I'd consider it. As it is, I'm buying 3GB mobile data add-ons for $49....which allow us to watch several hours of programming almost without interruption - when we encounter this ever-buffer. Usually, we don't as we access it during off-peak times. I do admit the $500/month Telecom bills (landline, broadband and mobile) are becoming "interesting". But we're seeing value there....or we wouldn't pay it.