I have a SB6121 and had 4 channel bonding on the downstream which worked flawlessly and I was pulling over 40 MBit's down.
I move 1 or 2 miles away, barely even 5 minutes away, and have no bonding at all and am only pulling 24 MBit's or so.
I bought this modem because of the bonding and without bonding, the modem is useless to me and I wasted over $100.
I'm at a total loss... I've called support multiple times and no one can seem to figure out why I am not bonding on the downstream. The only "decent" answer I got was that there are too many people on the node I am now on.
reply to MJimLay The modem will bond with the channels so long as they are there to bond to. This has absolutely nothing to do with how many people are in your area - sounds like a rep has facts confused.
If you already reset the power and the modem still doesn't pick up any of the channels bonding then as digiblur stated the node probably isn't set for D3 yet.
If you are paying for ultimate speed then you have a case with a legitimate issue. If you don't then....well good luck because you are likely getting proper/higher speeds anyway.