I have a 400/80 FTTP connection and recently started having buffering issues on the Fire Stick especially on 4K/Ultimate, last night the device checker fails for 4K.
The Fire TV Stick 4K Max is wired so limited to 100 Mbps, speedtest in Netflix app is 95 Mbps.
I watched a bunch of matches a couple of weeks ago including in 4K on Amazon, no issues.
Tested in desktop browser (wired) on BT Sport 1 Live:
Last night (Liverpool v Newcastle) browser (wired) was hitting t1live-im-5e48c600-bts1-euwe1.prd.us.ll.streams.sport.bt.com and getting slow speeds (up to 7 seconds to download 3MB)
Clearly wasn't always showing the highest quality and I think it was a lower frame rate than normal.
This morning (cricket) in browser (wired), streaming 1080p no issues.
It seems to use different CDNs, it was hitting t1-live-euwe1-us-ak-streams-sport.akamaized.net which also hits servers inside ISP.
If I stop/start it then it might use a different CDN, e.g. t1live-im-5e48c600-bts1-euwe1.prd.us.ll.streams.sport.bt.com
Either CDN seems to be downloading 5MB chunks of video in <300ms about every 6 seconds (e.g. about 16MBps or 133 Mbps).
Working fine against Limelight CDN this morning, ~20MBps
curl https://t1live-im-5e48c600-bts1-euwe1.prd.us.ll.streams.sport.bt.com/***removed***.m4s --output file.dat
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4803k 100 4803k 0 0 19.3M 0 --:--:-- --:--:-- --:--:-- 19.3M
*.ll.streams.sport.bt.com seems to be Limelight CDN and still seems to hit servers within my ISPs network (6 hops, 1ms to 41.63.110.76)
I did notice on some packet captures from the Fire Stick that sometimes it hits Limelight servers in Manchester, I'd guess it knows it's at capacity so sends the traffic elsewhere, it doesn't seem to work well since it ends up back on the overloaded servers again.
My feeling is there seems to some capacity issue at times when Limelight CDN is used.
Is anyone from BT able to investigate or ask your CDN partner (Limelight) to check KCOM capacity?
