Broadband downstream speed appears to be capped

[trevw]

I have BT Fibre 1 package which, when I took it out, was running at around 16Mbps downstream.

A few weeks ago I noticed downloads were slow and found that we were getting 12-13Mbps according to the BT Wholesale speed checker and the speedtest initiated from the hub. I raised a ticket with BT and an engineer came out, changed the DSL socket, did a few tests, proclaimed everything working and left. I left it a few days but there was no change in download speed. Since then I've had an OpenReach engineer and two more visits from BT Home Tech guys. None of them seem able to tell me why the speed is so low, nor why the download speed appears to be capped at 15Mbps, despite the router saying the maximum attainable speed is in the range of 37-38Mbs. I'd really just like to know why the download speed is capped so that I can make a decision about whether or not to leave BT after the month of sub-guarantee speed is up.

For reference, here's the Technical Log from the Home Hub:

Router Technical Log

As far as I can tell, the DSL connection is being reset every night. Here's the snippet from last night's Event log:

And from the Availability Checker:

I'm pretty sure that someone, somewhere is capping the download speed. Having spent some time on the phone with BT, they said it's not them. The OpenReach guy claimed it wasn't OpenReach 🙄

So now I'm at a loss as to how to progress this. I can exit my contract with BT on Dec 18 if they haven't got the speed above their guarantee, but on checking other providers, they were offering 12-13Mbps downstream, so the only benefit of leaving would be to save money on the package.

Does anyone have any ideas as to why my downstream appears to be capped at 15Mbps and how I can go about finding out why?

TIA, Trev

[licquorice]

Your line isn't 'capped' as such, DLM has taken action to stabilise your line due to a probable line fault and multiple disconnections. Is your line noisy when you dial the quiet line test 17070?

[imjolly]

Your connection time is only 14 hrs is that due to hub dropping connection or manual  reset or maybe a combination of both.

Try quiet line test. Dial 17070 option 2 should be silent and best with corded phone.

BT will not be capping your speed but if your line is unstable then the DLM will lower your speed to try and stabilise your connection

[trevw]

Thanks.
The line sounds quiet when I call 17070

[trevw]

Thanks for the quick response.
The hub loses the DSL connection every night. It was around 02:53 this morning and 02:44 the previous morning, 00:32 the morning before, etc.
This is not a manual reset and the power hasn't gone off

[imjolly]

The constant drops in connection is the reason your speed is low and until you find the cause your speed will not improve. Any DLM reset will bring speed back for couple of days but the constant drops will just take you back to square one.

Is there anything electrical that maybe switches on or off?

[trevw · Accepted solution]

Thanks for the helpful replies. I just wanted to close the loop on this one.

A second OpenReach engineer came out last Monday. He tested the line, then reset the card in the cabinet and our downstream speed jumped up to 39Mbps. According to the engineer, if there is an electrical glitch or power-failure in the cab, the card can lock the speeds at an unnecessarily low level. The clue (for him) was that downstream was exactly 15Mbps.

Since the engineer reset the card 6 days ago, we've had an unchanging 39Mbps downstream with 8Mbps up and the DSL line has not dropped at all.