My second 2740B is doing the same as the first.
First I can only achieve 3 Mbps since I live 10K' from the remote central office (RCO)
My line has been pruned all the way back to the RCO i.e it is in tip top shape.
I have a typical SNR of around 15.4db
My attainable speed is 5300+ Kbps
My rate is set to 3520 Kbps.
I have the latest firmware NA_2.06
I reboot the modem and I usually have 3 Mpbs
But 24 hours later is it down to 2.5 Mbps, another 24 hours and it is down to 2 Mbps, another 24 hours and it is down to 1.5 Mbps.
I reboot and it is back to 3 Mbps and the process starts over again.
I use testmy.net and run an hourly test from Lebanon, OR to either San Francisco or Los Angeles, same result.
Anybody have any clues?