ADSL2+ Disconnects - do the stats says anything?

Dear All,

As some of you already know, I have been having a terrible issues with frequent broadband disconnects on my line. A BT Engineer did visit, found a High Open and fixed. He then tested the line as good to go. A complete reset was done by BT and the line went back into training as if new install.

However, the disconnects still occur. I contacted Draytek (I have a 2830 Router) and sent SYSLOGS and other information and they logged on to my Router. They come back and said the SNR was 6db which is way too low. This also matched the logs as saying LOSS OF SIGNAL. I thought 6db was normal but maybe I am wrong.

Could someone tell me if the below stats look normal or am I really looking to see disconnects with these statistics?

--------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
Running Mode : ADSL2+(G.992.5) State : SHOWTIME
DS Actual Rate : 21923304 bps US Actual Rate : 679636 bps
DS Attainable Rate : 21796000 bps US Attainable Rate : 680000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 1 US Interleave Depth : 1
NE Current Attenuation : 0 dB Cur SNR Margin : 6 dB
DS actual PSD : 15. 0 dB US actual PSD : 12. 4 dB
ADSL Firmware Version : 2471201_A
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 2 dB Far SNR Margin : 7 dB
CO ITU Version[0] : 00004946 CO ITU Version[1] : 0000544e
DSLAM CHIPSET VENDOR : < IFTN >

Messy stats let me see if I have this right

Downstream attenuation of 2dB, margin 7dB
Upstream attenuation 0dB, margin 6dB

Connected at 21Meg down,. and 679Kbps upstream.

The Power levels (PSD) suggest modem has backed down from the maximum power, which is no surprise at that distance from the exchange, which is must be next door.

The 6dB will be the target, and so seeing that is not really a worry. More importantly is does it vary over time, so time to check the router logs to see if there is any history, if not try router stats lite to monitor the router. Failing that login in perhaps once an hour particularly when dark and keep a note of all the figures.

What concerns me is that the upstream is lower than I would expect, so it is worth checking your wiring in the home, and that everything is filtered, and also seeing if using the master sockets test socket helps with the stats.

Thanks for the reply.

The low upstream was the sync speed immediately after a disconnect occurred. I have since powered off the router (in a controlled fashion) and the new up speed sync is 1Mb and the down is 21.5Mb.

The SNR does not really vary - seems to stay pretty stable with the occasional drop to 5db and then back to 6db. However, I would say it�s pretty static. It is certainly not going up or down by 2 db every hour. Every time I log on day or night 6db SRNM is a common figure.

I have the luxury of having 2 lines into my premises. One owned by TalkTalk and the other is BT Wholesale. The BT one is where I am having an issue. It is almost like I need the line to sync at 12db with a lower rate and then it will be stable. However, something (at the exchange?) keeps thinking the BT line is stable at 21.5Mb and 6db. I know that probably sounds rubbish to you experts but it might help give you the feeling on what�s going wrong.

In way of an example, the TalkTalk line does exactly this. That connection is at 12db SNRM and sync around 18.5Mb � as you expect, higher the SRNM the lower the sync speed. Interestingly enough, if I plug my BT connection into the TalkTalk Socket, it also sync's at the same speed and SNRM as the TalkTalk connection � 18.5Mb/12db. In short, whatever is on my BT owned line (or what it talks to at the Exchange) thinks my line is stable and can stay stable at 6db. It can�t and loses connection around 5 times a day.

The BT DLM considers 10 or more disconnects in an hour unstable.

If happy to sacrifice speed then ask the ISP to raise the target noise margin to 12dB,

My line certainly does not disconnect at that frequency so the DLM would consider it stable. I might only get 5-10 in a whole day.

I will ask my provider to increase target SNRM to 12db and let�s see what happens.

I will report back later with an update � thank you for your help so far.