another thing i found great with my 834G v4, although as you probably all know it ill put it in this thread rather than start a new one. if your snr drops a little bit at night (mine goes down by three or so) and you have SRA (seamless rate adaptation) enabled in dmt tool. your sync will lower (at least mine did) to meet the lower margin. so turn it off via the snr tab and bobs your mothers brother!
of course i guess this means that if your lines snr goes too low you will flat out d/c but in my case the sync would lower itself to 3000 at night (down from 3600) i lose one stage of IP profile and overall not a great thing. with sra off it stays at 3600 and the snr reduces from 10 to 7+- which is still fine. (with it on it would keep the snr at 10 while lowering sync - without resyncing)
so if you have a fluctuating sync rate, which is causing you to lose a stage or two of ip profile. turn sra off. if it gets unstable simply turn it on again, but it worked great for me
on the flip side if you get lots of DCs and don't mind losing sync speed maybe turning it on would work. but this is merely a hypothesis
P.S.
I hear some isps don't support SRA (im on BT) so your mileage may vary, also i imagine it will work with other routers but i cant test that