recently had bt infinity 1 installed, laptop via wi-fi, 30mb/sec download and about 9 upload,
old Dell Dimensions 2400 series pc, wired via extension cable from the bottom of stairs (main bt socket) to bedroom ,speed = 6mb/sec down, about 1.5mb/sec up.
is this entirely down to the old pc, or is the internal wiring causing this issue ?

Are you sure you are measuring the same thing? Do you mean Mbps or MBps. mbps would *very* slow.

Assuming you mean and are measuring Mega-bits per second in both cases then I would suspect the network card in the old desktop. If the desktop is reporting Mega Bytes per second then those figures sort of match up with the laptop measuring Mega bits per second there being (usually in this context there being 8 bits in a byte).

oops correction Mb/s on speedchecker

I assume you mean you have run an ethernet cable from the router up to the PC? Ethernet using decent quality cable should be able to handle 100Mb/s up to 100 metres or so.

Therefore if the cable is good quality and you haven't done anything to damage it during installation or run it under carpets and that has worn out the cable with people walking over it then you should be getting rather more than 6Mb/s (I'll assume you mean Megabits not millibits ).

One possibility is that the network card in the Dell is a 10/100Mb type and has got stuck in 10Mb mode somehow. Not entirely sure how you would set it to 100Mb mode though.

High Speed RJ11 to RJ11 BT Broadband Extension Cable Lead, from bt master socket, to home hub 5 in bedroom, then ethernet cable from hub to pc ?
now im thinking this is not correct

You might be losing a little bit of performance doing it that way but that will not be the cause of the difference between the two computers.

You could try plugging the lead you are using on the PC into the laptop, turn off WiFi on the laptop to force it to use the cable connection, then try the speed test. If you get 30Mb or more on the laptop then that implies a problem with the PC.

If not then try a different port on the router and if still no difference try a different lead. It's essentially a game of trial and error to see which link in the chain is causing the difference.

many thanks for your patience and much appreciated advice, will give it a try,

I've seen this with v. old pcs - I think they just can't process the data fast enough.

The PC I use in the study is over 10 years old and having tried just now I get 34M download and 5.6M upload so it does very much depend on the spec rather than age alone..

Looking at the Dell spec it should easily be able to run a speed test.

I'm not saying that this is the issue, in fact I'm sure it's not, but the correct installation would be to have the HH close to the master socket and then run ethernet cable around the house.

If this were the issue then the wireless would be equally slow given that the problem would be in the wiiring before the hub.