sbiddle: My first post on this?thread says a lot.
With respect, your first post on this thread pointed at window scaling issues, and hinted at the default (whose default?) window size of 64K being the problem.
I've pointed out (repeatedly) that firstly, the window size concerned here defaults to 128k (ie, ~6mbit/sec), and secondly, that both ends correctly support TCP window scaling. So, no, your first post is not actually all that helpful.
sbiddle: Your connection is delivering 15Mbps, and will happily do 15Mbps UDP or using multiple TCP connections. I don't see how it's not performing.
1. The server and every step of the way back to my end point have the capacity to deliver 15mbit/sec.
2. We assume that at every step of the way, no shaping, dropping, etc, is occurring. Shaping = dropping for reasons other than congestion, and dropping otherwise is the result of congestion, which by (1), doesn't occur
3. Consequence of 1 & 2, dropping, if it is occurring, is only occurring due to shaping.
4. TCP is performing slower than 1 & 2 would suggest.
5. Consequence of 2, 3 & 4, Shaping must be occurring.
6. Telstra swear black and blue they don't shape.
7. Consequence of 5 & 6 (assuming we believe them!), someone else must be shaping.
8. Server can deliver full speed to a different provider
9. Consequence of 8 - shaping occurring is not done by the server's ISP or uplink providers.
10. Consequence of 9 - It's Telstra's problem to sort out.
11. They haven't.
PS: Here's hoping they do sort it. Shifting is such a pain.