Reduced Downstream speeds

[#1]

The line profile is actually 5500Kbps.
Can you please raise a fault by going to http://faults.plus.net giving as much information as possible?

[#2]

Fault raised
Edit:  I think I may have discovered something. I tried a different microfilter between my router and the master socket and this reduced the Noise Margin to 6.3dB.
So looks like a rogue microfilter - only problem now is that the sync speed is still staying at 6655. I have rebooted the router several times and it doesn't change.
Could the speed be being fixed by BT at the exchange?

[#3]

Are you sure the noise margin of 6.3dB isn't the upstream value? If it was downstream I'd have expected sync speed to increase significantly.
I think you could be rebooting your router far too often; this might be causing the exchange DLM kit to treat your line as unstable resulting in your target noise margin being increased to try to stabilise the line. The effect of this is reduced sync speed.

[#4]

mmm - weird it was definitely my downstream Noise Margin that had gone to 6.3dB but now it is back to 24dB.
I have now tried 3 different microfilters directly into the test socket to eliminate both microfilters and my internal wiring.

Quote from: spraxyt

I think you could be rebooting your router far too often; this might be causing the exchange DLM kit to treat your line as unstable resulting in your target noise margin being increased to try to stabilise the line. The effect of this is reduced sync speed.

I also think it must be something at the exchange that is increasing my Noise Margin and thus my sync speed.
When PlusNet ran a test on my line I noticed this in the results:

Quote

Current line rate 5500 Line rate change timestamp 19/02/2009 10:29:21

I was having connection issues on the 18th and 19th  so I wonder if they did something to my line then.
I am hoping that PlusNet and BTw can sort this out between them.

EDIT:  Things have now taken a turn for the worse - my Noise Margin has increased to 28dB and my sync speed has decreased to 4475kbs

[#5]

I have a theory - could someone with better knowledge than myself confirm whether this could be the case.
On the 18th Feb I had some connection issues (not sure why) - because of this the DLM at the exchange automatically raised my Target Noise Margin which reduced my sync speed to 6675.
As I was trying to sort this out I kept rebooting my router which caused the DLM to assume I had a connection problem so it kept my Target Noise Margin high.
Once the PSTN engineer had been to "solve" my "noisy" line then I kept re-booting my router again to try to resync. This constant rebooting actually had the opposite effect as the DLM at the exchange assumed my reboots were because of disconnects and has now automatically increased my Target Noise Margin again (now at 28dB) and thus reduced my sync speed again to 4475.
If the above theory is correct how can I get BT to reduce my Target Noise Margin back to 6dB as my line was perfectly stable at this for weeks.
Brian

[#6]

There's no such thing as a target noise margin of 28dB.  It doesn't actually go that high.
No hamr in raising a fault and asking for your target noise margin to be reset, if you're happy that your PSTN issue has been fixed.

[#7]

If you haven't re-synced in the last 24 hours I suggest doing so just once, then record sync speed, noise margin and attenuation. Sync speed should be higher than you have now and I expect you will find noise margin is around 15dB implying that is the current target.
If your connection remains stable as Jameseh said you can raise a fault asking for the target noise margin to be reduced on the basis that the PSTN fault has been fixed.

[#8]

Did that and things haven't really changed - Noise Margin is now 30dB and speed is 4544  :'(. I am running RouterStats now to collect the info I need.
I already have a fault raised with PlusNet over this and they have now passed it on to BT - so hopefully they will find something
adie:quote

[#9]

Nice one.
Let me know how you get on and I can always ask someone to have a look if need be.
There's got to be something drastically wrong for your downstream noise margin to be as high as 30dB.

[#10]

Thanks James - will do.
Also I did a quiet line test (17070 option2) just to make sure and my line is completely silent so definitely not a PSTN fault.
Just another thought the only thing I haven't ruled out is the router - is this likely? I don't have access to another one and I don't want to have to buy another one if it isn't the problem.
Brian.

[#11]

We can alwaus loan you a router after getting BT to do some basic checks first.
We'd be apprenhensive of sending an engineer without trying a different router.

[#12]

Try a different router and a different cable that is connecting your router to the wall socket too!

[#13]

Wow - not sure what has happened but my Noise Margin has reduced to 8.7dB and my sync speed is now a whopping 15126. I am assuming that BTw have done something - whatever it is I hope it stays like that.
Brian

[#14]

That's good news; hope the noise doesn't return and screw things up again next time it rains.
David