I assume you still have a dangly filter from ADSLx days. There is nothing to stop you removing the VDSL2 faceplate and using that into the test socket. See how that does.

Oh we certainly have - if nothing else from the bog-standard ADSL backup at the bottom of the stairs

When my glamorous assistant gets back, I'll set him on it. Thanks for the idea!

I don't understand how most of these suggestions are relevant if the BT speed tester (which is always the worst of the lot for me) is showing 36Mbps.

BT speed tester says 36 meg is being pumped out to us.

Until last weekend, in the house we could utilise about 30 meg of that 36.

Since last weekend, we can only utilise 18 meg of it. This is verified by other non-BT speed-testers, downloads, etc.

The in-the-house speed has demonstrably dropped.

We have eliminated (apart from the modem PSU) every piece of kit this side of the master socket hole in the wall.

Something is preventing us seeing more than half of what BT says its delivering to us.

Therefore something somewhere is either lying to us, is misinformed or is confused. But whatever else, downloads we do the same each week which used to take 30s now take 50s, regardless of time of day. This is commensurate with a useable level of 18 and not ~30 meg.

In reply to a post by Orddu:

Therefore something somewhere is either lying to us, is misinformed or is confused. But whatever else, downloads we do the same each week which used to take 30s now take 50s, regardless of time of day. This is commensurate with a useable level of 18 and not ~30 meg.

It may or may not be related to your problem but about a month ago speedtest.net was saying my download speed was only 23Mbps rather than the usual 38Mbps.

I went round the whole check the connections, recycle modems, routers but no matter what I tried I got 23Mbps.

A little bit later I was on another machine in my house, a rather smaller HP Microserver and I got the usual 38Mbps. Thinking whatever had been the problem had resolved itself I tried again on my main server - 23Mbps. Seemed to point at my main server as being the problem, network card failing or something.

I tried a different browser, Chrome and got 38Mbps, IE9 was 38Mbps, FF10 (I think) 23Mbps. So a problem with FF on one particular machine. Deleted and reinstalled FF and straight back up to 38Mbps where it has remained ever since.

No idea exactly what the problem with FF was, but it was indeed a FF problem - nothing to do with my connection at all.

In reply to a post by Squirrel:

No idea exactly what the problem with FF was, but it was indeed a FF problem - nothing to do with my connection at all.

Firefox (and the Flash plugin) was perhaps configured to connect through a proxy.
And that added a considerable overhead to the speedtest results?

cheers, a

Tried on 3 different machines, Chrome, IE9 and FF. All roughly the same results (variation very small).

This is the same whether the internal network is connected, or whether it goes wall socket > modem > PC (Zen even took the router out of the equation yesterday and we connected straight into the modem briefly).

In reply to a post by kasg:

I don't understand how most of these suggestions are relevant if the BT speed tester (which is always the worst of the lot for me) is showing 36Mbps.

I agree with you in theory, but

When you have eliminated every possibility, whatever is left, no matter how impossible must be true

A principle I frequently found true in relation to computing and data networks.

We've also had the faceplate off the master socket and connected with a microfilter to the phone socket inside. Still no change, so it's not that either.

Which leaves something shonky with BT or something shonky with Zen really. Everything our side of the BT wiring has been eliminated.

Have Task Manager running with the network tab selected.

Run te following tests:

BT Speedtester
BT Beta Speedtester (twice) http://speedtest.btcentralplus.com/beta/
TBB Java
TBB Flash
Speedtest.net - Best server and then another UK of your choosing

Take a screen shot of the Task Manager window and post a link to the image.