iirc the red dots relate to the gainQ2 tickbox
Gain Q2 are figures provided by your router which show the value of the individual tone eg
gainQ2 start
tone 0: 0 0 0 0 0 0 0 101 83 84
tone 10: 112 109 89 112 90 112 99 99 95 106
tone 20: 103 97 91 91 87 98 100 112 117 88
tone 30: 95 90 106 114 85 94 107 84 93 105
tone 40: 86 88 95 106 110 84 96 101 111 85
tone 50: 91 96 101 111 86 94 106 0 0 0
tone 60: 77 102 100 100 115 100 100 100 100 100
tone 70: 100 100 100 100 100 100 100 100 100 100
tone 80: 100 100 100 100 100 100 100 100 100 100
etc
>> why does the upload graph drop-off beteen 32 and 50 tones ?
Noise at those frequencies, or the line length is too long to support speeds above what youre currently getting, therefore the signal isnt strong enough?
>> Is there a digital filter on the upload side at the exchange that causes this behaviour ?
Sorry, not quite sure what you mean there. afaik Be only filter (block) tones 476-499 for some obsure reason.
If your line can support it then it should show a nice smoothish curve.
From what Ive seen on my own line, once the bins are much below 5ish on the graph, (or 20 on the SNR graph) then the signal isnt strong enough. See how the last bit allocation is normally 5 as the signal decreases and 5 is the last one it can "hear".
tone 500: 9 9 9 9 9 8 7 8 7 7
tone 510: 6 5
bitalloc end
Your own downstream appears to have ended abruptly - probably around tone 476 mentioned above.