I have a long, unstable line which was actually helped when ADSL Max came in, as it allows sync down to 160bps downstream. For a long time the profile was set by BT's automated system (the name of which I forget) to include interleaving. This is probably a good thing? However, for the last year or two it has invariably set as Fast Path. When I asked my ISP (now assimilated into Talktalk Business) to change the profile to interleaved, they said they could not do this as it was entirely under the control of BT's automatic system.
Now I was aware that some people who preferred Fast Path for latency reasons were upset in the past as this was automatically changed to interleaved, but I was unaware of the opposite change being automatically applied. Are Talktalk right (it had to happen sometime ...)? Or is there any advantage to Fast Path I haven't thought of, such as allowing lower sync speeds?
I thought I would ask the experts here to get my facts straight, before perhaps taking it up in an ISP forum.