Zyxel Noise Margin

you can also slightly tweak the target snr margin to connect a lower rate and increase stability.
With adslmax it only seems to work when increasing the snr.
 
wan adsl targetnoise X
 
where X is between 0xfa (-6) and 0x06 (+6) where each point is .5db of snr, so..
 
0xfa reduces the target by 3db,
0xfc reduces the target by 2db,
0x00 does nothing,
0x02 increases the target by 1db,

wan adsl targetnoise 0x06  =  command  is meant to increase the target SNR by 3db

wan adsl close
wan adsl driver dnmaxbits 10
wan adsl open

(where n is 0 to 15, 0 is slowest, 15 is fastest)

All the dnmaxbits 10 command seems to do is cap the rate per tone to “a” which affects the faster lower tones but not the higher ones which are probably the most marginal. What I really want to do is increase the SNR in exchange for a slower speed. The command  is meant to increase the target SNR by 3db but it makes no difference I can see.

wan adsl opmode ( check dsl standard status)
ADSL_G.dmt / ADSL2+

Depends on which ISP you are using.  you may need to change it to GDMT mode.

1 telnet to the zyxel = click ‘start’ then ‘run’ and type ‘telnet 192.168.1.1′
2 login (password is the same as the web interface)
3 type ’24’ – to access the system maintainence menu
4 type ‘8’ – to access the command line
5 type ‘wan adsl opencmd gdmt’ – sets the adsl to gdmt.
6 save, exit, then power off the modem and power it back on