Declining ADSL Speed

[#1]

What's happening now with my ADSL? It feels as if it is being throttled for some unknown reason. Long ago now I accepted my original 18,000 kbps SNRM 3 dB line had gone for good (Why?) and grew used to my 'new' 6 dB 15,000 kbps line. But now I cannot even get that! Although there seems no indication of any fault or even serious error rates I seem stuck on less that 15,000 kbps as, whenever I reconnect my Down SNRM now heads to ~8 dB.

Why should this be happening?

(I do notice a rather large 'hole' at about 1483 kHz/Tone 384 in the bitloading plot)

Up speed: 1231 kbps - Up SNRM: 6.3 dB - Interleave (Down/Up): 1/0
Down speed: 14335 kbps - Down SNRM: 7.6 dB - ES/hour (Down/Up): 32.1/0

[#2]

That 'hole' has partially backfilled now. I also notice bit swaps centred mainly around the same frequency range. Reading Kitz on "Bit Swaps" suggests they are caused by noise bursts on particular tones. So is this the answer?

As I sometimes see periods of no bit swaps perhaps I should reboot my router then?

[#3]

I'm no expert... but I would say that if SNRM was 6 when you last retrained then the best thing to do would probably be to retrain next time that peaks (like now!)…it will negotiate back to 6 and you will get the extra sync rate!

Of course, next time the line gets noisy your SNRM will drop and so might your connection.

Is it worth the extra few hundred Kbps when the line is quiet or do you prefer to have the stability (even at noisy times) that the extra margin provides?

[#4]

It seemed very quiet today, bitswap wise, so I rebooted.

Down speed: 14335 kbps - Identical!

So it's 14335 kbps or nothing? Currently it's looking like they are the only two options. What's going on? Is this going to be another of those ADSL mysteries - like my fixed IP address?

The SNRM is moving to match a fixed speed - the speed is, currently, just not changing.

Down SNRM started at 7 dB, qickly moved down to 5.5 dB, gradually moving up again (heading back to 8 dB)

Same hole in bitloading spectrum as before - some bitswaps, again in same place...

[#5]

Shut down router overnight, rebooted in morning. Do I have to tell you my download speed? No!

14335 kbps - Identical! Curiously, this morning, that hole in Bitloading map has gone.

So, currently my ADSL 2+ download speed is pegged to an absolute and fixed speed that cannot be renegotiated. Why?

[#6]

Curiously, Kitz says there is a banded profile very close to that number (Kitz ).

[#7]

@pvmb It is almost certainly banded at that speed, if you sync at the same speed after a resync. Plusnet can remove the banding.

[#8]

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@Anywho wrote:

Curiously, Kitz says there is a banded profile very close to that number (Kitz ).

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Yes, 14336.

Kitz says banding is applied to lines that have difficulty maintaining sync at a higher speed. But I wasn't having difficulty at 6 dB, so I will ask if the banding can be removed. Plusnet!

Thanks.

[#9]

BT Wholesale Speed Test - On WiFi, but still:

Advance Test

Download Test
Download speed achieved during the test was 1.97 Mbps
For your connection, the acceptable range of speeds is 4 - 21 Mbps
IP Profile for your line is 12.65 Mbps

Upload Test (This never makes sense)
Upload speed achieved during the test was 0 Mbps
IP Profile for your line is 0.83 Mbps

Oops!

[#10]

@pvmb Which modem/router are you using? can you post a screen shot of the data page - obscuring personal data, of course.

Sounds like there is something slightly deeper going on.

[#11]

Router is Technicolor TG582n, Data from DSLstats:

John, Can't format correctly here - Notepad file attached

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[#12]

@pvmb Apart from the low uptime I can't see much wrong there, It is a while since I've used a 582N, but don't they have a page that gives all that data and a bit more in a more readable format? I'll have to go looking at my old image uploads to find the one I'm talking about, so I'll be back if I can find it.

Something like this:-

[#13]

Only this - as above:

Broadband Connection

DSL Connection

Link Information

Uptime: 0 days, 12:23:06

DSL Type: ITU-T G.992.5

Bandwidth (Up/Down) [kbps/kbps]: 1,231 / 14,335
Data Transferred (Sent/Received) [MB/MB]: 10.89 / 85.51
Output Power (Up/Down) [dBm]: 12.9 / 0.0
Line Attenuation (Up/Down) [dB]: 14.4 / 28.5
SN Margin (Up/Down) [dB]: 6.0 / 7.9

System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN

Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -

Error Seconds (Local/Remote): 442 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 57 / 596
HEC Errors (Up/Down): 131 / 4,009

[#14]

Thanks - much easier to read than the DSLstats report.

I haven't read all the topic (sorry), but are you seeing a lot of PPP drops - you presumably had one about 12.1/2 hours back?

A Radius graph (and possibly a KBD report) from PN staff may be useful.

[#15 · Accepted solution]

Thanks for your post @pvmb

I'm sorry to see you're having speed issues.

I've tested your line today and the tests aren't showing the cause for this, but I can see your line is indeed banded at "WBC 7M - 14M No delay (INP 0) 6dB Downstream, UC No delay (INP 0) 6dB Upstream (ADSL2+)"

I've arranged to remove the banding now, which should go through within the next hour. 

With regards to your fixed IP address, I believe I solved that mystery for you Here (you have the broadband firewall on)

Let us know how it goes.