My line was upgraded to 21CN ADSL2+ on 14/2. The day prior I was happily connected at 6688 Kbps on ADSLMax, with a 5.5 Mbps IP profile (happy days).
Following switchover, the SNR target was immediately raised to 9dB, then rose to 12dB, but has steadily dropped since. Earlier this week, it dropped to 3dB, which is stupid for my line length, but there goes to magic of DLM.
The problem I have is that at some point on 18/2 I noticed I was getting a reduced actual download speed, and ran a test on BTW's performance test site. I was surprised to see that the full test results reported:
Download speed achieved during the test was - 4.31 Mbps
For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
IP Profile for your line is - 3.78 Mbps
This with a downstream connection rate of 6432 Kbps.
At no point since 18/2 has the IP profile rate or the acceptable speed range changed. It is still the same at the time of writing.
The line connection rate is simply not reflecting an IP Profile of 88.2% of the connection speed - which it was from 14-18/2.
My ISP seems to have drawn a blank/given up, and simply cannot offer any explanation as to what is going on. Has anyone seen anything similar or got any advice as to what to do next?