Live opposite the exchange yet only get 12Mbps

Since I moved to a flat that's quite literally next to the exchange I figured that I'd get pretty decent ADSL2 speeds, yet the best I seem to be able to achieve is around 12Mbps (BT checker) which according to CS is just fine. Is this right, or has something gotten a bit messed up?

BT results:

Download speed achieved during the test was - 12.74 Mbps
For your connection, the acceptable range of speeds is 4 Mbps-21 Mbps.
IP Profile for your line is - 13.48 Mbps

Upload speed achieved during the test was - 0.69Mbps
Upstream Rate IP profile on your line is - 0.83 Mbps

Modem stats (Downstream/Upstream):

SNR Margin (0.1 dB): 97 127
Attenuation (0.1 dB): 100 59
Output Power (0.1 dBm): 215 122
Attainable Rate (Kbps): 22224 24107
Rate (Kbps): 15285 828

Mode: ADSL_2plus

SNR is 9.7dB that why u get lower speed. If u are with Plusnet, u can ask Plusnet to get your SNR reset target at 3.0dB to gain more speed.

How long have you had the connection? If it is in the last few days then it may improve automatically.

Otherwise it looks like something is holding back your speeds - asking Plusnet to lower the target SNR may sort it. Can you get the stats immediately after a reboot?

About a week or so, my best guess is that it might have something to do with me having to fight with my modem to get it to work bridged (turns out the trick is to ignore Plusnet's guidance and pick LLC-Based multiplexing) leading to a bunch of disconnections in the first couple of days, but it's been pretty stable since.

Unsure if it's related, but after asking interleaving to be switched off, a Service Notice popped up on my account noting that I'll be moved over to 21CN by midnight tonight, though according to CS it's already happened. Not really sure why it wasn't from the start..

In reply to a post by hopkapi:

a Service Notice popped up on my account noting that I'll be moved over to 21CN by midnight tonight, though according to CS it's already happened.

It has already happened. Otherwise you'd only be getting 8 meg Sync speed.

Your line is good for about the full monty 24 Meg @ 6dB NM. Your current 9dB NM does not account for the 8-9 Meg reduction you are getting, perhaps only 2-3 Meg of it. However wait a days to see if it settles.

Are there any working extensions in the flat ? Have you tried plugging into the test socket behind the lower part of the BTmaster socket, in order to eliminate any internal extension wiring and also the faceplate it's self, ? As said give it a day or so , if no improvement then try the above ,
also have you performed a quiet test using a corded phone 17070 option 2, ?
if there are any noises such as crackling or other noises that are odd present there may be a fault with the line itself

As for your speed, that is currently being restricted by the current Bras IP profile which is set by Bt's woeful DLM Your connection has probably been interleaved which won't help with getting max speeds,
Also the Upstream sync appears to be capped, ask your isp to uncap it , you may get a 1mbps usable upstream rate then ,
If the IP profile doesn't increase then i think the ISP can get it reset , or maybe even disable DLM altogether ,

But IMO getting around 13mbps throughput with a sync of around 14.5-15mbps with a short line, and attenuation figures like yours isn't just fine at all, fine for who the isp?

Edited by tommy45 (Wed 21-May-14 18:19:47)

In reply to a post by ian72:

How long have you had the connection? If it is in the last few days then it may improve automatically.

Unlikely. All variants of xDSL start out at full speed and generally only drop over time.

In reply to a post by tommy45:

As for your speed, that is currently being restricted by the current Bras IP profile which is set by Bt's woeful DLM

Slow down Tommy .

The Bras IP Profile is set by the connection speed, not the other way round. Connection speed (15285kbps) x 0.882 = 13.48Mbps which is the IP Profile displayed.

Nothing at all wrong there. The reason for the low connection speed is what we need to look for. Sort that out and the IP Profile will track it.

The diagnostic tests you suggest might help.

Edit - IIRC the 828kbps upstream might be the maximum on BTW interleaved.

Edited by RobertoS (Wed 21-May-14 23:03:14)

In reply to a post by RobertoS:

Edit - IIRC the 828kbps upstream might be the maximum on BTW interleaved.

Usually, but not always (E7er sometimes had higher but I've never seen it), 888K (or sometimes 444K with half-speed PN ).

Agreed, IPProfile is not a problem or a cause. I just ignored Tommy's fallacious argument .

Edited by XRaySpeX (Thu 22-May-14 00:08:17)

We know when tommy is wrong, but the OP, or a later chance reader, may not . So it had to be refuted.