Sorry if this has been answered before.

I want to be able to monitor the line statistics of my ADSL2+ connection and potentially use the upstream/downstream speeds to alter the QoS settings on my router (a homebrew linux-based device), as they seem to vary with the weather. I could screen-scrape the status page on the html, or do something similar via telnet, but I note that the modem broadcasts status information via UDP to port 4944 every 10 seconds on the LAN side. I believe it can be used by a Draytek router to display line status from the modem.
Unfortunately the data seems to be scrambled in some way - successive messages look nothing like each other except for the first 4 bytes. I wonder why this is, and whether there is information on how to descramble it.