Tweaking ADSL2+ performance on Billion BiPAC 5200S ADSL router, via telnet CLI (same chipset as ZyXel P660R-D1?, Speed-Modem 50B?) Telnet to the router's IP address to access the CLI. View relevant line data: router> show wan adsl chandata near-end interleaved channel bit rate: 0 kbps near-end fast channel bit rate: 2062 kbps far-end interleaved channel bit rate: 0 kbps far-end fast channel bit rate: 903 kbps router> show wan adsl linedata near relative capacity occupation: 100% noise margin downstream: 17.5 db output power upstream: 12.3 dbm attenuation downstream: 44.0 db MANUALLY ADJUSTING LINE RATE FOR ADSL2+ The default setting is normally 0 0 Check your existing setting before making a change: router> wan dmt2 set snrmoffset -1792 -1792 Subtract 512 from both values to reduce SNR margin by 1 dB: reduces speed, increases stability Add 512 to both values to reduce SNR margin by 1 dB: increases speed, reduces stability Example: Auto-negotiated SNR margin was 17.5 dB Reducing margin by 14 dB should increase speed: -1792 + (14 * 512) = 5376 router> wan dmt2 set snrmoffset 5376 5376 router> wan adsl reset After re-sync (1-2 mins), view line data again to compare: router> show wan adsl chandata near-end interleaved channel bit rate: 0 kbps near-end fast channel bit rate: 5017 kbps far-end interleaved channel bit rate: 0 kbps far-end fast channel bit rate: 911 kbps router> show wan adsl linedata near relative capacity occupation: 100% noise margin downstream: 5.4 db output power upstream: 12.3 dbm attenuation downstream: 44.0 db Noise margin actually reduced by about 12.1 dB to 5.4 dB; downstream line rate is now 5017 kbps! (up from 2062 kbps) If connection fails to resynchronise, retry with a setting that allows for a larger noise margin (usually it seems at least 3 dB is needed for day/night atomospheric variation of radio interference in the phone line; preferably 6 dB, or even more if strong local sources of interference are causing frequent resyncs. Use 'attentuation downstream' figure plus the chosen target SNR margin to estimate theoretical maximum rate for a line in perfect condition: * http://www.kitz.co.uk/adsl/max_speed_calc.php eg. 44.0 dB (from data above) + 6 dB (my chosen target SNR) = 50.0 dB; estimates 5152 kbps as the best achievable rate. To make changes persistent, the CLI contains a basic text editor for autoexec.net which contains CLI commands that are run automatically after a full reboot of the modem: router> sys edit autoexec.net EDIT cmd: q(uit) x(save & exit) i(nsert after) d(elete) r(eplace) n(ext)