So I'm having a running argument with Compass Residential and Chorus about whether the problem is my line or Chorus's network that is the issue.  The last Chorus tech "proved" that my router (a Siemens Gigaset sx763) was at fault, so I borrowed a D-Link N750 from work and tested that.  The Gigaset would sync at full rate but frequently disconnect and refuse to either re-sync or PPP authenticate.  The D-Link retains its connection (I assume it's autoreconnecting) but syncs at half the attainable line rate and encounters frequent DSL transmission errors that cause the connection to be virtually unusable.

Standard questions:

This is naked DSL.  There is a single jackpoint to which the router is directly connected (no master splitter, no inline filter).  As no voice service is provisioned on this line, and no voice devices are connected, my understanding is that this is considered acceptable.

Six routers total have been tried.  Five of them would simply disconnect and refuse to reconnect, the Gigaset being the most reliable of these.  The sixth, the DLink, has slow speed and high transmission error rates.

A total of - from memory - seven faults have been logged with Chorus, all of which have resulted in basically nothing - a tech comes out, fiddles with things, and then blames my equipment and leaves.  I have had precisely ONE positive experience with a chap who managed to get my sync rate from 3Mb/s to 14Mb/s by replacing some jumpers/joints, but he himself said that the line is essentially buggered and needs replacing.  (Fun fact - I've had so many faults logged that I have the cellphone number of the regional manager for the area!)

Below is a dump of the statistics screen.  I assume that you'll all confirm that what I'm looking at is definitely a faulty line, but it'd be good to have some confirmation (especially from some telco type folks!) - confirmation from ChorusVan would be an exceptional bonus (beaten only by them actually fixing the blasted problem).