Which margin is which?

Does anyone know which of the margins shown below is the one dictated by the DSLAM? This is a Draytek 2820 router and I'm assuming it is the 'Far SNR Margin' but I'm not sure... surprised if it is 18dB but would explain why I can't sync at 8128 any more:

> show adsl ?
  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
   Running Mode            :    G.DMT       State                : SHOWTIME
   DS Actual Rate          :  7584000 bps   US Actual Rate       :   832000 bps
   DS Attainable Rate      :  7584000 bps   US Attainable Rate   :  1324000 bps
   DS Path Mode            :        Fast    US Path Mode         :        Fast
   DS Interleave Depth     :        1       US Interleave Depth  :        1
   NE Current Attenuation  :        9 dB    Cur SNR Margin       :       15  dB
   DS actual PSD           :    17. 9 dB    US actual PSD        :    12. 5   dB
   ADSL Firmware Version   : 232201_A
  -------------------------------- ATU-C Info ---------------------------------
   Far Current Attenuation :        4 dB    Far SNR Margin       :       18  dB
   CO ITU Version[0]       : 00005453       CO ITU Version[1]    : 00005443
   DSLAM CHIPSET VENDOR    : < TI >
>
> show status
<snip>
ADSL Information:      ADSL Firmware Version:232201_A
Mode:G.DMT             State:SHOWTIME   TX Block:12937479 RX Block:291268337
Corrected Blocks:18    Uncorrected Blocks:24
UP Speed:832000     Down Speed:7584000    SNR Margin:15  Loop Att.:9
>

TIA.

Hi

Both margins (upstream and downstream) are dictated by the DSLAM. However on the downstream margin it is possible to change it with some modems/routers.

Perhaps the DSLAM has given you a 12 or 15db margin due to the line being unstable at some point, you will need your ISP to reset this (not always easy to do) or with some modems you could cheat it.

Regards

Phil

Thanks Phil.

Just wish I knew what the triggers were to avoid it happening - I do get (CRC) errors but seems generally < 0.002%.

I went through a phase of firmware upgrades/downgrades at one point but way before it increased, and yes, been through the mill with Entanet - given up there.

Thanks for the response.
C.