Up until a couple of days ago I had a stable ADSL2+ connection at c.17Mbps connection speed. My router then went into a continuous re-sync cycle (i.e.; loss of internet, DSL training, DSL established). It would hold the connection for a minute or so and then start the whole process again. To my surprise, rather than fall, my downstream connection rose to 18.3Mbps but the time between re-synchs reduced. Prior to the problem, I had a stable downstream LA of 18 and SNR of 3. My ISP has run line tests but they have not detected a fault, There is no noise on the line.
Through my router settings, I have tweaked my line for stability over performance. My target SNR has risen to 6 and I have a relatively stable connection at 16.4Mbps: that said, I am still getting downstream errors. Yesterday's router log shows 69 resynchronisations - most of these between 7 and 10 am.
When I reduce the target SNR back to 3 instability returns and the connection rate rises to an unstable 18.3Mbps - a figure never seen before on my line. The downstream CRC error rate also increases to thousands per hour.
Could this be a DLM fault. If so, what is the best way of getting it resolved at no financial risk to me?