So what is it then?
From the limited RouterStats graphs you've posted, it looks remarkably like the problem I had with REIN some months back, skewed though by you apparently having a fixed SNR margin? I notice that the 12 hour graph doesn't show a problem during the night i.e. when humans are mostly asleep. Is that always the case?
What's happening now that you have a 9dB margin?
Is the connection now holding but with the noise margin dropping every so often by ndB?
Can you post an RS graph that's sampling every 10 secs and set so that there's about 30 mins across the graph please? It might be interesting to see what the drops look like in more detail when they occur and then stop.
My problem was caused by a faulty computer monitor switched mode power supply in a house about 100yds away - every time they checked their mail or used the PC I got clobbered by up to 8dB - it was only when the offenders went on holiday for two weeks that I worked out where it might be after a two week interference free holiday (along with a number of neighbours who had the same problem)! The owners hadn't bothered to address the warning signs that the monitor kept inconveniently switching itself off after an hour or so and was getting hot...
Have your tried listening with a MW radio (within which the ADSL frequency range lies) and see if you can hear some strong buzzing noises when the connection drops out and you then tune around from about 600kHz up?
I don't ever recall anyone posting recordings of REIN, apologies if someone has? If you want to know what you are listening for (for my case anyway) here are two MP3 format recordings, first with no interference and the second with, both tuning up and down the MW band, using a small pocket Roberts radio which was useful when walking around the area with an earpiece trying to trace it:
QUIET Recording
ACTIVE REIN Recording
The original thread on my problem is
HERE. Since locating it I've not lost the connection once, even when dropping to below 1db overnight.
Sorry if this ends up being of no help though.
Tony
Hurstpierpoint, West Sussex
My Live Router Stats
ZeN Active 40dB 2.9Km
Billion Bipac 7800 @ 1 - 3dB
