Looks like (to my untrained eye) the line has been stable overnight since the resync, but there are still some errors. My IP profile has dropped by the 10 meg as expected which leaves me still within the clean range of the availability checker.
Yup - all looks cleaner, with a manageable ES rate.
- Is the 10 meg lost forever or if the source of the interference is removed will my attainable rate rise again?
If the drop in SNR is permanent, then your loss of speed is too. With such a sharp change, and having stayed that way since, it looks to be permanent; as long as that user keeps their modem powered.
- If the drop is due to crosstalk, am I likely to see such a drop each time a new line is connected to the cabinet? It seems quite a drastic drop.
The effect of each new subscriber is random, as it mostly depends on the construction of the cable bundles that your line pairs share - how close together the pairs lie, and how long a distance they share that proximity. This means you might see large drops or small drops, in any order. This particular drop does seem very large, so I wouldn't expect many of that order; luckily the latest one seems to have had little impact.
From the way FTTC is deployed - with tie pairs between the FTTC cab and the old PCP, we know that there is always some amount of line shared, and that it is at the most susceptible point, when the transmitted power is at its highest, so we should always expect *something*.
Overall, the graphs used to show how effective vectoring is, also show how bad crosstalk can be - with the worst case speeds being half that of the theoretical best case. Thankfully, the worst case does not happen much, and you should mostly expect to stay within your clean range estimates.
- Should I consider a different modem, would a more up-to-date device extract more from the line? I got the HG612 cheaply just to see what was going on with the line after the BT hub started misbehaving less than a day after installation.
It probably isn't needed. The broadcom chipset in the HG612 doesn't seem to be markedly worse than anything newer.
