The problem with SFI, is that it is loaded against the user. The ISP cover themselves with an up to £180 potential cost on which you have to rely on honesty.
I have moved ISP on two occasions and had problem resolved without issue. In both cases reported noisy line by ISP. In first case line had been banded.
I would do a line check first , from BT website, if BTW, With broadband removed and at master socket.

In reply to a post by timthewebb:

When troubleshooting I would see reconnection speeds at 13Mbs (which is about right for my line), however, after about 5 mins these would step down to 3-4Mbs

Line stats below (running Dratyek 2830):

ADSL Information ( ADSL Firmware Version: 2471201_A)
ATM Statistics TX Cells RX Cells TX CRC errs RX CRC errs
7758727 35461560 0 3
ADSL Status Mode State Up Speed Down Speed SNR Margin Loop Att.
ADSL2+(G.992.5) SHOWTIME 687714 4147513 13 21

TX CRC errors 0
RX CRC errors 3
Up Speed 687.7Kbps
Down Speed 4147.5Kbps
Up Attenuation 13dB
Down Attenuation 21dB
Up SNRM 14dB
Down SNRM 13dB

If my translation of your router stats are correct, I don't see how you reconnect at 13Mbps then it steps down to 3 or 4Mbps after 5 minutes. Does the router resync several times during that 5 minutes leaving you with the stats quoted above? Or are the stats always like this now after a reconnection/resync following your troubleshooting some time ago?

In reply to a post by 4M2:

Up Attenuation 13dB
Down Attenuation 21dB
Up SNRM 14dB
Down SNRM 13dB

Don't see how you can derive 4 figures out of 2?

I can only read 13dB Down NM & 21dB Down Attn.

In reply to a post by XRaySpeX:

In reply to a post by 4M2:

Up Attenuation 13dB
Down Attenuation 21dB
Up SNRM 14dB
Down SNRM 13dB

Don't see how you can derive 4 figures out of 2?

I can only read 13dB Down NM & 21dB Down Attn.

Yes I was just trying to find the missing SNRM figures so I just took the last 2 numbers from, which appear to be, both of the sync speeds - this seemed a possibility. Perhaps the OP can confirm that supposition or correct it?

Peculiar!

Most likely they are missing as some routers only report the Down figures.

In reply to a post by XRaySpeX:

Peculiar!

Most likely they are missing as some routers only report the Down figures.

Indeed the up SNRM and up attenuation figures probably are missing in which case sync speeds possibly are 687714bps up and 4147513bps down

Edited by 4M2 (Fri 28-Jun-13 21:12:34)

That's how I took it (bps) earlier in the thread, going by the column headings. Note that if you click the Quote button you see the post displayed as intended, before html rendering screws it up).

Then when I saw your figures, I wondered, and came to the same conclusion as you re the speed/margin figures.

On further reflection I think I was right first time. I checked the reported throughputs against the bps figures before my original post and they looked about right.

I expect the missing data is available, just wasn't posted.

Whatever, even on bps + down att + down SNRM, the speeds don't compute.

Edited by RobertoS (Fri 28-Jun-13 21:05:53)

Yes, I'm sure XRaySpeX is correct when he mentioned that some routers don't give upstream attenuations and upstream noise margins (which is something that I wasn't aware of )

Never-the-less I still don't understand how, what is presumably throughput speed, steps down after reconnection to between 3 and 4Mbps from 13Mbps given a reported sync speed of 4147513bps by the router?

I suspect the router or the MSAN line card is going duff.

Line card fix should be free - a router problem if a SFI finds the line to be in good order could prove to be expensive!