New customer - half the speed of previous provider?

[#1]

I've just switched to PlusNet and I'm a little concerned about my new download speed.
On my old ISP I was getting a reliable 4Mb download, with the router syncing at something over 5000 and a S/N of about 11dB (I forget the exact figures).  My estimated speed when I signed up to PlusNet was 4Mb, which corresponded with what I was already getting.
Since the line was switched to PlusNet on the morning of 5/2/2011, speed tests have shown my download speed has been at a pretty constant 2Mb.  At first the router was showing similar sync speed and S/N as before (5000+ and 10 or 11, again I didn't take note of the exact figures) but my download speed wouldn't go above 2Mb.  Later that morning, the router resynced at 2400/448 with a similar margin.  The next morning it had dropped to 2368/448 and has stayed there ever since.
I realise I'm in the middle of a 10 day "training" period where the speed is supposed to go up and down, but the last time my line was subjected to one of those, it settled on a speed straight away and never changed.  I'm now worried that I'll end up with half the speed I had before I switched.  Is it likely to return to the stable 4Mb I was getting before the switch, by the end of the 10 days?  If it does settle on 2Mb after the 10 days, can it increase in the future or am I stuck with it?
My current stats (I've now noticed it's just changed again, but still 2Mb):
Line Mode: G.DMT 
Latency Type: Interleave
Line Coding: Trellis Off
Line Rate: 2400 Kbps down / 448 Kbps up
Noise Margin: 6.1 dB down / 22.0 dB up
Line Attenuation: 49.0 dB down / 28.0 dB up
Output Power: 17.9 dBm down / 11.9 dBm up
Thanks in advance for any advice!

[#2]

Quote from: AJones

On my old ISP I was getting a reliable 4Mb download

Was that LLU/ADSL2+? Who was the provider?
If it's just a switch on the BT platform there's no 10-day training period.
(around 5mbps would indeed be typical for your attenuation)

[#3]

It was Pipex and it was ADSL Max "up to 8Mb".  I think it may have been LLU but I'm not sure.  They migrated a lot of customers to LLU without informing them when Tiscali took over and speed test sites showed my ISP as Tiscali, so I may have been one of them.
Something I've just remembered - I was put on a 20CN connection when I migrated to PlusNet because there is currently no spare 21CN capacity at my exchange.  Apparently I will be moved to 21CN when the capacity becomes available in a couple of months time.  Am I correct in thinking that 20CN = ADSL Max and 21CN = ADSL2+?  If so, is it possible my speed will return to what it was when I move to 21CN?

[#4]

Hmm, it's still not right.
I'd ask PN if it is "training", if so wait out the 10 days.

[#5]

Hi AJones,
Your first connection was on the 5th so you will still be in  your 10 day training period Your SNR is currently 12dB which will be keeping your sync down. How is your connection set up. Are you using extension sockets/ cables. Do you have a test socket you can plug into?
Jojo

[#6]

Hi Jojo, thanks for your reply.
If it's just the training period, I'll be happy to wait out the 10 days and see how it goes.  The speed still doesn't seem to be changing, though.
My router is a BT Voyager 2110 and is plugged directly into the master socket.  I am not using extensions and don't have any other equipment (not even a telephone!) connected to the line.  Is the test socket the one beneath the front panel on the main socket?  There's only one behind there if I remember correctly, and the front panel plugs directly into it.
Edit: Just noticed you had linked to a picture of a test socket!  Yes, I believe I have one like that.  Is it OK to try it out while I'm still in the training period, or will my deliberate disconnections cause a problem?
Anthony.

[#7]

Hi AJones,
I would say it's best to be in the test socket. However, we have seen many many problems with the voyager 2110 and our faults guys haven't a good word to say about them as quite often when there's a fault and the customer has one of them we've sent a test router and it's cured it. So I'd definitely see if you've another router you can try too.
Jojo

[#8]

Thanks Joanne.  I don't have another router I can try at the moment, but I'll try the test socket when I get the chance and report back.
Anthony.

[#9]

I've now been using the test socket for the past three or four hours.  On reconnecting after plugging into the test socket, my router stats changed to:
Line Rate: 5088 Kbps down / 448 Kbps up
Noise Margin: 6.3 dB down / 22.0 dB up
Line Attenuation: 49.0 dB down / 28.0 dB up
Output Power: 19.9 dBm down / 11.9 dBm up
This is much more like what I was getting before (apart from a lower noise margin) and suggests I should have a higher speed.  However, when I run speed tests, they show I'm still getting 1810Kbps down and 258Kbps up.  I saw something similar within the first few hours of my PlusNet line being activated, before the router reconnected at 2400.

[#10]

It will take a while for your profile to catch up with the better synch rate - what are the results of (1) a BT Speed Test and (2) your Plusnet profile (stable rate)?
(Edited to add) If you are seeing better synch at the test port, it's likely that you either have a fault somewhere in your internal wiring, or an unfiltered device connected - Sky digital box, phone, fax - or a faulty filter on an extension.

[#11]

Quote from: Jaggies

It will take a while for your profile to catch up with the better synch rate - what are the results of (1) a BT Speed Test

Download speedachieved during the test was - 1860 Kbps
For your connection, the acceptable range of speedsis 1200-4000 Kbps.
Additional Information:
Your DSL Connection Rate :3472 Kbps(DOWN-STREAM), 832 Kbps(UP-STREAM)
IP Profile for your line is - 3000 Kbps
The throughput of Best Efforts (BE) classes achieved during the test is - 22.18:20.82:57.05 (SBE:NBE:PBE)
These figures represent the ratio while sententiously passing Sub BE, Normal BE and Priority BE marked traffic.
The results of this test will vary depending on the way your ISP has decided to use these traffic classes.

Quote from: Jaggies

and (2) your Plusnet profile (stable rate)?

Estimated line speed:
3.5Mb (This may vary between 3Mb and 7Mb) - Checked on 2011-01-26 17:36:21
Current line speed:
2 Mb
The 3.5Mb estimate surprised me, as all previous estimates I was given were 4Mb.

Quote from: Jaggies

(Edited to add) If you are seeing better synch at the test port, it's likely that you either have a fault somewhere in your internal wiring, or an unfiltered device connected - Sky digital box, phone, fax - or a faulty filter on an extension.

There have never been any other devices connected to this phone line (not even a phone!).  The only thing that's been eliminated from the loop by using the test socket is the faceplate on the BT master socket.  I have to wonder if the new stats have more to do with me disconnecting and reconnecting the router than using the test socket (especially given the new margin).
The BT speed test seems to be saying that the maximum speed I can get is 4000Kbps - yet I was getting between 4 and 5Mb on this line before switching to PlusNet.

[#12]

You have your answers in your first couple of posts
1) you thought you might be on LLU
2) when you joined PN

Quote

I was put on a 20CN connection when I migrated to PlusNet because there is currently no spare 21CN capacity at my exchange.

so you must have been on LLU, on a straight ISP transfer you would not have changed your exchange connection
LLU uses a completely different technology, TT have there own switchgear in the exchange

[#13]

So does that mean my connection now can't support 4Mb any more?  Even though that's what the estimated speed was when I signed up?  That's very disappointing if so.  Do you think that switching to ADSL2+ in the future will make a difference, or is finding another LLU provider the only way?

[#14]

Use Samknows to see which LLU providers are in your exchange.

[#15]

you are in your training period and your router says this
Line Rate: 5088 Kbps down / 448 Kbps up - that is the possible synch speed
so you might still get 4M  and when you eventually go on 21cn it could - note could go higher as 4M is on the cusp