You are mistaken there goldenadsl, DLM will not have lowered you SNRM to 1dB. DLM uses 3dB steps. On first connection or on reset it starts at 6dB. It can go down to 3dB on 21CN not 20CN. On 20CN it can go upto 15dB and 18dB on 21CN.
If that 1dB margin is pretty much constant, I can only assume that your last resync occurred when the noise that your line normally picks up was a lot less than normal and it returned to normal shortly after, hence reducing the margin. This is based on the fact that the sync speed you have is much higher than one might expect for a line of that attenuation. The other possibility is that your Netgear has the ability to be set to ask for a lower Target SNRM.
