Since the process of retrieving DSL values has completely changed between 19.07 and 21.02 and the set of scripts I originally wrote for this purpose will not work anymore ... I completely rewrote it.
Files and instructions are at
I now have a luxury problem: The DSL line to the device on which I am testing this terminates only a few meters later in an FTTB box and the line hardly ever throws any errors. The errors graphs do work, and they should display meaningful data (they are a direct transplant from a related setup), but I have no way to judge it. Feedback is very welcome.