Download Speed loss

I was recently put on BT fibre. Prior to that I got 17mbps download. On fibre I only get 20mb. I contacted BT who sent an engineer, who did not seem too confident in what he was doing. (I am 300mts from cabinet)

He initially said there was no fault on line, then spoke to someone on phone, and agreed there was line fault. Went away for an hour and said it was fixed. He said he was getting 28mb at main socket, but I was only getting 20.

His conclusion was that because the router is on an extension (3mtr, wired by BT, not plug in) that is why I lose the download. This is the only extension, and has filter.

Before I complain to BT can anyone tell me if he is correct, or fobbing me off.

Thank You.

What speed to you pay for as I get 65meg but if you on speed limited account you may not get that. The main fault will be the cable from socket to router you need a shielded cable which looks like a usb cable that can make a massive difference, the router should go into the master socket or loss and noise will reduce speed. Its simple to test just plug router into master socket and test. If the loss is internal wiring bt will charge you £90

Partly true you might say. You may have a noisy line or something like that. That is usually indicated by higher S/N ratio or noise margin.
Normally the Modem/Router has a stats page you can look at for that number.

I am in a similar position 600 m from my Green cabinet/box taking an assumed route to my house.
Currently ADSL2 ? connection is 16 Mbps.

The BT website for BT fibre says 35-36 Mbps guarantee of 30 Mbps.
For a bit more dosh(~£5/mth) 36-50 Mbps guarantee of 30 Mbps.
That £5 does not get you much.

BT do tend to blame a users internal wiring almost as a matter of course.
Their only responsibility is to your Master socket. Past that it is yours whether you have a BT modem/router or not.

I have about 8 metres of phone extension cable(previous owners) and it only makes a difference of at most 1 Mbps, so I don't care about that.

If the bell wire is used that will do as it's not used now but if connected acts as antenna for noise also if the extension pass electric cables that can do it

If I take the front off the master socket and plug router in there I get 28mb, but if I connect router to the socket on the front of the master i get 18mb. Faulty master socket? Surely they should both be the same?

I assume you mean you take off front plate and plug in and get 28 meg and assume the retention is wired into front plate in which case the extention is the problem

OK, thank you for your help

Depends whether you have a filtered master socket, mine is not and makes no difference, the filter is at the end of the extension lead.
Sounds like you have a fault in a filtered master socket, probably the filter.
That is BT kit which they have to fix. You will have to be firm about that.

There are various master sockets the latest ones isolates the extension wiring.

Thank you