Line capable of higher download speed.

Hello All! My first post so hope I doing it right!! I need ideally an Open Reach engineer to hopefully explain my predicament. I'm with TT on the upto 76MB fibre connection and have the HG533 router running ver. v1.15t. My speed was 70/19 then just dropped to a steady 45/19. I complained via their forum and an Open Reach eng. was sent who checked the cabinet etc. and got the speed back upto 70/19, Great!!. BUT the speed has once again gone back to 45/19. I complained once again and was sent a new router, this put the speed back to 70/19 for 5 days and now it's gone back to 40/19. I know the line is able to sync. at 70/19 because I saw the speed via the Open Reach engineers line analyser and he confirmed this. So my question is why does it keep on dropping and staying at 40/19, I'm also signed up with SAMKNOWS so have detailed line metrics.
Please can one of you clever Ladies or Gents throw some light on this. Thank you in advanced, hope all the above makes sense!!

First, I'll disabuse you of a couple of false notions:

1) Being signed up with Samknows might give you a lot of speed data, but you don't have a wealth of line metrics.

Speed tests give you, at best, a hint that a problem exists. They do nothing to tell you what the cause of the problem is.

Detailed line metrics would help there, but the regular Openreach modem hides those. The best that can be done with a BT-Wholesale-based line is to perform a BTW speedtest, and extract the IP profile, from which a sync speed can be calculated.

Unfortunately, even this piece of information is unavailable to TT lines.

2) FTTC speeds start high, and pretty much only ever get lower.

There are multiple reasons, even on a line that isn't faulty. Line faults can add an extra dimension to speed reduction, and intermittent line faults can both cause speed reductions *and* be incredibly tricky to fix.

Reason 1: DLM usually watches for 2 days before intervening. If your line has a high error rate, or even high packet loss, then DLM can intervene. Speeds can be reduced by anywhere between 10% and 30%.

A visiting engineer can order DLM to be reset, at which point it monitors for another 2 days before intervening again.

Reason 2: The major cause of noise and interference to an FTTC line is other FTTC subscribers. This causes speed reductions as take-up increases.

The problem is that the speed reductions seen are, effectively, random compared to the take-up, so the extra reduction can happen with just one or two other subscribers out of 100.

Speed reductions here can be even higher.

Reason 3: You might have a faulty line.

So... what does this mean?

When you see a speed of 70 on an engineer's JDSU, you can't expect to keep it. You need to see the error rate too, to have an idea of whether the speed will be kept.

These are the line metrics you need from your modem: Sync speed, CRC error rate/count, FEC error rate/count, and the FEC/interleaving settings ordered by DLM.

Is any of this available from the HG533 router? I don't know this router very well (or the TT service) ... is the router acting as a modem?

If DLM has intervened, it will have set a line profile for the modems to follow. I've seen Plusnet get hold of this information from Openreach... can TT get it too?

Is any of this available from the HG533 router? I don't know this router very well (or the TT service) ... is the router acting as a modem?

I have the HG533, its TalkTalk's equivalent of the BT HomeHub 3. It dosent have any FEC or error recording statistic panes unless on your connected through ADSL.

Edited by deleted (Fri 18-Apr-14 15:52:47)

OK, that tends to make it hard to diagnose any TT problem without getting TT support involved, and an Openreach engineer out.

Those speed drops are large enough for Openreach to investigate, at least.

@2wayman:
What was the original estimate? That will probably dictate whether Openreach will continue looking.

Edited by deleted (Fri 18-Apr-14 16:04:55)

Wow!! Thanks for such a detailed reply, I see what your saying and you are quite right in the JDSU measurements. I did'nt see or know about error rate unfortunately so no help there. I have a separate Open Reach modem and I don't think the router has any info about Sync speed, CRC error rate/count, FEC error rate/count or FEC/interleaving.
So as a layman what should I do, get the DLM reset. The bottom line is I may drop down to the upto 38MB package as I just getting that now a save a few quid every month!
Thanks again WWWombat

Is the 38mbps product "unlimited"?

Which modem is it, ECI or Huawei?If it's the Huawei HG612 they can be unlocked easily and then you can get to the proper stats.

Edited by R0NSKI (Fri 18-Apr-14 19:57:05)

Huawei if you both please .

Corrected. I can never remember and seeing as I was eating my dinner I couldn't be bothered to Google the correct spelling .

Yep Unlimited