How are you testing the single thread download - always from the same [windows] PC? If so then I would test from a different wired device if you can. Or download and burn a bootable linux CD, like Knoppix, and boot your PC from that and test download again, just to rule out anything your end.
1, I seriously doubt it's my PC or the ethernet connection to it, it isn't my router either
2, I don't at this present time have another working PC to test anyway Unless someone is going to reimburse me for buying one or building another ie new board and CPU then it won't be happening i am sick of this nonsense It is something zen's side or BTW's less likely the kit including the cab to the exchange cable links
UPDATE:
I think that i have through my own process of elimination testing found that this issue with single thread performance for myself at least is almost certainly not any of my equipment it's not the line either, last night after switching my LAN connection to my PC from routing via my router, to a direct link to the BT modem instead and i found that there is no issues, i had previously reverted back to the normal modem ><router><PC config, and still retained normal throughput, i did this last night , at 6.00 am dlm re-enabled G.inp and speedtests on zen's different lns gateways, were back to the rubbish single thread performance,
I have just tested directly to the modem, and 1 gateway i am getting normal ss performance and on the only other i able to hop onto The performance is poor on single stream ,
It's also odd that after the engineer had finished testing from the test jack , that i had the poor ss performance across all gateways, until connected directly and swapped gateways as it connected to the same one on the 1st attempt ,
It has to be something configured incorrectly which happened when they migrated my circuit