I have an ADSL link that for years has run at just over 6Mbps downstream, except when there are drop outs but these are rare. Over the last few days my speed dropped to less than 3Mbps.
Using Routerstats into my Technicolor router showed the RX Sync Speed as 7872Kbps and RX Noise Margin of 6.2dB. However, the Bits/Tone is really strange. Normally this would indicate most downstream tones in the region of 12 bits. But during this slow period I have about half the low end tones at only 1-2 bits; then a gap of about 40 tones with 0 bits, then the rest of the high end tones of 9 bits.
I spoke to John Lewis/Plusnet who ran lots of tests - supposedly - and found no problem and agreed with my sync speed. After some technical discussion in which I'd pointed out that I had tried another router on the master socket which showed the same problem they wanted to ship a new router. Again I pointed out that I had tried and alternate. Anyway they classified this as No Fault Found from their end and suggested an engineers visit with the caveat that should they not find any fault I would have to pay £65 if NFF. I wasn't totally happy as BT are constantly mucking about in our exchange but I agreed.
Now, is it a coincedence that a couple of minutes after I ended the call my downstream speed returned to the usualy +6Mbps. However, the bit loading still looks odd with the same pattern as previously.
Anybody care to comment on why I have my normal speed but poor bits/tone showing in Routerstats.
I cancelled the engineers visit just in time.