Thanks neilius, I already did that and got a couple mb more out of the upload speed, still slower than what I had before though.
Interesting g3uiss because now I think about it, I'm pretty sure I got full speed from the HG612 when I first initially set it up to test if it works, I then went back to double NAT while configuring the new router. Only got the lower speed after rewiring everything to set it up to permanently use the new modem, had some issues and it may have got reconnected a few times, perhaps DLM kicked in then and there is actually nothing wrong with my HG612? I'll keep an eye on it and see if goes back up to the higher speed.
If DLM is the cause, do you think a higher performing Broadcom chip with double NAT is worth it over a much older Broadcom chip and single NAT?