Hi, I have TP-LINK W8970 v3 and it turned out that telnet command for SNR adjustment doesn't work for this router.
But, I have found that SNR can be adjusted via Broadcom DSL Diagnostics App - see the link from italian site:
http://www.hwupgrade.it/forum/showthread.php?t=2684120Translated from Italian:
SNR modification program with Broadcom
by mik77
Download the program BcmDSLDiag.
Broadcom BcmDslDiags 1:42
Broadcom BcmDslDiags 1:43 (only executable)
Unzip the downloaded archive into a folder.
Open the MS-DOS prompt in that folder.
To access the router telnet and type the command
dsldiagd start
Launch the program from the MS-DOS prompt with these BcmDslDiagsL.exe paramteri
BcmDslDiagsL.exe -s IPOFYOURROUTER
Once you launched the program must go BcmDslDiagsL.exe nell'interfaccai web Modem menu
Tests> xDSL PHY Configuration
Training in the field Margin (Q4 in dB) is set to hexadecimal value you want to set (help with a converter)
Ex. 100 made your default margin for example if you want to increase it by 50% must enter 0x96 (150 in hex is 96)
If you want to get off, say 80%, you have to put 0x50 (80 in hex is 50)
I have tried ajusting the SNR values with hexadecimal values, only just managed to remove a few db but not by 9 db or so. I'm not sure if it needs to have specific values (for hexadecimal) to be entered?