I've just been thinking about this some more...
As most people here probably know, BT use IP profiles to limit your download bandwidth, usually to slightly below your actual sync speed. Now I'm not entirely sure about this, but I think one of the main reasons for this is so that their end (i.e. the exchange/cabinet) knows how much data it can push down your line without overwhelming it. Without that (or some other way of managing it), I think downloading any file with no bandwidth limitation would consume your connection's entire download bandwidth, holding up other packets and causing the sorts of issues we're seeing here - high pings, packet loss etc.
So I now strongly believe that the actual cause of the issue (at least in my case, and anyone else who's seeing the same sort of speedtest behaviour) is that something, somewhere along the connection path (but probably at a lower level than the IP layer, so not a particular hop that would show up on a traceroute or anything like that) is dynamically limiting the available download bandwidth. Rather than just allowing the maximum possible bandwidth at all times, it seems to be reducing that to somewhere around 10-20mbit/s as soon as the connection goes idle (or when it goes below that speed I guess?). And then it's taking about a second to adjust that upwards when it sees that more bandwidth is needed, which causes the high latency and packet loss in the meantime.
When I first started having this problem, after ruling out all equipment and everything on my side (right up to the master/test socket), I suspected it might be a faulty line card in the fibre cabinet. But obviously now we know that lots of people are having the same issue, so it can't really be that - but it does seem strange to me for it to be anything much further along than that.
So perhaps it could be caused by a firmware update that was applied to the line cards? But then it seems when people have moved to other ISPs the issue has gone away, and they would still be connected to the same line card (I think?) and using the same BT Wholesale/Openreach/whatever it is hardware in the cabinet and exchange etc, so I guess not. So something further up within BT, but which is being applied to each connection individually... some sort of traffic management-type system (gone a bit wrong) I guess?
I also don't know who within BT would actually be able to do anything about it - I haven't even tried to contact them directly myself to even let them know there's an issue yet, because I know that's just going to be incredibly frustrating and not get anywhere unless I can speak to someone higher up, or it becomes a known issue that they're actually aware of.
I just think it's a problem with BT's backhaul network. I've got six months before I get out of this hellish 18 month contract and can finally switch ISP -___-
Just updating the forum and mods following changes made to my profile during the early hours of Friday. Sadly, there has been no difference to performance and the below graphics clearly show the difference when idle and streaming.
The below are before, during and after streaming Netflix in 4k. The pingplotter results speak for themselves. It's like night and day.
After streaming (stopped at 9:54)
Personally I'm more convinced that the BT network is tuned / setup for their TV box and watching sport, dropped packets are totally not going to work for a saturated network so they buffer at some point in their network to make sure users watching sport don't end up with dropped frames / stuttering playback. BT are competing with Sky, they're investing some major cash in sport, there's no way they can be known as the sport / TV supplier with stuttering playback.
Luckily / somehow my connection was fixed a while a go, everything went from slow and sluggish to snappy over night, my speed was unchanged. So I'd just keep complaining, keep raising formal complaints, keep ringing up BT, keep getting engineers to visit. Overall the easy fix is to just leave BT, if you're under contract you might as well keep complaining - what you should be looking for is to exit without fees.
Leaving without fees will be a battle because BT don't care about ping, it's not even considered, all that matters is 'speed'. When talking to anyone at BT keep referring to their advertising "Perfect for streaming, gaming, watching and downloading in HD on multiple devices", that's assuming you're on "SUPERFAST FIBRE 2" or above. As I did tell them they're claiming your connection is "Perfect for gaming" when it's not even usable gaming and a million miles from being "Perfect". Keep pressing for being allowed to leave without fees or a fix...
Don't use the online / live help it's a waste of time for this issue, try to be put through the technical people when you ring BT, generally the front line staff have no clue about ping, they'll just tell you that your speed is good and you have no fault.
If you've identified this issue and have a means of testing a fix then you're in a good place, it's easy then to verify if BT have fixed the issue or not.
Yep ive been having this problem now for over 8months, it seems to be a big problem and apparently BT have only just realised it or found out about it so I really hope they fix it before the new CoD comes out...
Here is another page about this problem, hopefully the more we post on BT forums the more recognised it becomes and they fix it quicker
I have tried buying a Netgear xr500 Router with Qos to try minimise bandwidth on the TV that is streaming netflix and prioritised my Xbox but it doesnt do anything really, everything is also wired but makes no difference. Paying all this money for Fibre and it isnt even doing its job for nearly a year is crazy
New routers, Qos, different network cards, network tweaking, limiting bandwidth using other methods such as 'net limiter' won't solve this. Limiting bandwidth can help a little but the result so minimal and random it's not worth the effort. The only thing that worked for me at the time was keeping my LAN 100% silent apart from gaming.
BT know what this is - they fixed my connection, the before and after is like night and day, shame they still can't manage it for everyone or admit what the problem is.
By keeping your LAN quiet you just mean not using anything apart from your console?
It sucks cause in my area BT is about the only decent provider so i dont have much choice but I do want to cancel cause paying for this is just pointless
I have to say, mine now seems to be fixed.
BT said they were changing some of my profile settings last thursday/Friday night but when testing again on the Friday morning these seemed to have little impact.
Last Saturday, I switched back to the master socket (oddly in the bedroom) and it is working fine. The odd spike but nothing like it was.
Bandwidth shoots straight to maximum whereas before it was a gradual crawl.
I haven't yet tried connecting back to the old socket but will try to do so see whether it makes any difference.