In reply to a post by ukhardy07:

THIS IS MOST ISPs

Many thanks for such an insightful response.

David

In reply to a post by TheEulerID:

Historically, 6dB has been considered a normal target SNR margin, but on good, stable lines 3dB might be set. However, on a poor line you might see as much as 12dB margins. That is generally not a good sign as, not only does it lose speed, but it probably points to a line subject to lots of interference from sources of noise (often sub-optimal extension wiring is at fault).

So, the sync speed will remain constant until a re-sync. You might expect to see SNR margin vary; maybe by the off couple of dB. In general, that has not impact on throughput.

If you have very high SNR margins (of the order of 12dB), then you have issues with variance in noise.

Thanks for this. My line always seems to want to be at 6db but the ISP, (SKY has advised that it is set to 7. I am able to change the SNR at the router end but no-matter how I set it, it always starts at 7 or 8, depending on the margin variance I set at the router but drifts down to 6 where it levels out, sometimes for 18 hours, but then starts to drift downwards again to around 2db. Once it gets that low, it doesn't recover so I end up re-booting.

In reply to a post by pdes:

Another cabinet picture for your gallery! https://goo.gl/maps/1JMF6

Thanks . I shall add that soon.