Synch speed down to 1000 Kbps why?

[#1]

Might be worth trying it without the surge protector plugged in for a few days to see if that makes any difference.
Just to echo what was said above, on a line like yours, removing interleaving is likely to make things worse.

[#2]

I'll give it a go when I get in.
and plug the sirge in between the router and the PC.
Don't suppose any work has been done at my exchange recently as it was happily motoring along at 1500 until recently.

[#3]

Go to your exchange and ask them if they have done any work?
We'd have no way of knowing tbh with you.

[#4]

Sorry I'd assume from a service provider perspective you'd have access to a BT system containing this info as I've got diddly squat chance of them telling me if I try to contact Openreach and you folks control that line anyway now.

[#5]

It's basically unlikely to be down to BT work.  But barring routine maintenance, we wouldn't be informed of any work.

[#6]

as someone else quoted on this forum, the words of the wise late Douglas Adams.
Damn and blast British Telecom!