Significant download speed reduction in evenings

I am within a mile of my local adsl max enabled exchange and for most of the day get a download speed of 6,5 Mbps,. In the evening I quite often find that the line gets very sluggish and I am down to between 0.9Mbps and 2Mbps as measured on a number of Speedtesters including the one on this site. Line stats remain the same. However when I try the BT Speedtest it always shows figures between 5.5Mbps and 6.7Mbps. Does this suggest that the problem I am experiencing results from my ISP routing/congetsion rather than line problems. There are no reports of my exchange having congestion issues.
I would appreciate any advice on this before taking this further with my ISP.

It could be either the ISP or the exchange.

Although the exchange might not have any reported congestion issues, they can be running hot before they are fully declared, ie only affecting a small number of users instead of everyone.

When using the BT speedtest, have you been prompted to run test three?

Matt

Thanks for the response. No I have never been prompted for Test 3 when using the Bt Speedtest. What I find difficult to understand is how the BT test consistently seems to give me a hight score even when the reality of browsing and downloading files and other speedtests are giving me very megre results in the evening period.

Alan

The speedtest won't necessarily take account of what is happening at the ISP. The ISP may not have enough capicity or maybe you have gone over some limit and they are throttling your connection.

What ISP is it?

If the BT speedtest is ok, then pretty much rules out exchange congestion, leaving the segments the ISP has control of as the usual suspect

My ISP is AAISP.

Alan

I had this problem with my previous ISP (as you can see) I assume it was
there traffic management introduced by stealth esp as speeds to the BT speed tester site. My solution was to switch to sky

I understand from the AAISP site that they have identified an evening congestion issue and are trying to resolve it.

Alan