Well up front I will say that I am astonished that your modem works at all. I've worked on ntl: BB for 6 years now and have never seen anything even close to being as bad as those readings!
Downstream -22.72 dB. The spec is + or - 15. -10 is borderline and I
think ntl: start thinking about sending out an engineer at -6dB. On its own this level should kill your connection with frequent disconections. The splitter you removed would have made this 3dB even lower.
(I know we tested the modems to -22dB in the lab a few years back, but we didn't actually expect them to do anything at that level.)
SNR 28.12dB. This is the best of the bunch but above 30dB is preferred.
Upstream 61dB this is the maximum output from a 120 modem. At this point it is "screaming" back at the network and as a result the signal is clipped and distorted. Again, on its own this level should kill your connection with frequent disconnections.
Conclusion - Forget firmware. It looks like* you have a serious physical connectivity problem. Because the downstream is low and the upstream is high the connection must be pretty close to open circuit. Its certainly high impedance.
(*An alternative could be that the modem power level measurement hardware is fried I suppose).
There is a really good Article on this at
http://www.chetnet.co.uk/articles/in...x_v2&id=42&c=7 although it has my name as the author it was written by Bomber. I just added the footer.
Peter