Types of line fault

Hi

I have a pretty bad line, 63dB attenuation, which was once able to provide 2500kbps or around that, but is now struggling to make 1400kbps (normal sync 1000-1400).
I am on UK online LLU, with a billion 7402 as these are said to work well with easynet stuff.

I am struggling to figure out why my sync speed has now gone to pot from what it once was. My SNR on my old router used to be steady at 7db at most speeds i connected at, even when i was syncing at 2000+kbps dipping to maybe 4ish at night at times. Now it can be around 8db but at times can be 14db.

Immediatly i thought my isp had set the target snr higher, but after ringing them they claimed this is not the case. My router is plugged directly into the test socket (i made a make shift prefiltered faceplate by plugging a splitter directly into the test socket and then plugging the old faceplate into the phone side filtering all the extentions.) I have ruled out the filter as have changed multiple times.

Finaly i get about 1200CRC errors over a 24 hour period, though not too sure how bad this is.

I dont get any drop outs.

The only thing left i can think of is a fault between the exchange and my house, though i am reluctant to ask for an engineer because i have heard unless there is a problem with the phone service it is very hard to get BT to do any thing and i could be stuck with the call out charge. I would just like to ask if this sounds like possible a HR fault? or any other type of fault on the line which could cause this drop in speed.

Cheers.
Greg

At 63dB attenuation you are at the behest of the DSL fairies really.

If the SNR margin is at 8 or 9dB within seconds of restarting the router, then it suggests the ISP has actually changed the target noise margin. Not uncommon for support to deny, i.e. it may be an auto system, or simply a side effect of a firmware upgrade and how your ADSL interacts with their hardware.

At that level of attenuation 3dB margin rise could easily account for 500Kbps or so of sync speed.

It is not a fault in Openreach eyes, they would look at line length details and simply say its the length of the line and there are no sync speed guarantees, you get what you get, and even if you had got 8128Kbps sync before they could simply say no fault under present system.