Can you do a managed reboot of the router? Rather than pulling the power or line cable, tell the router to reboot - that will ensure the DSLAM sees it in the right context and will not treat it as a loss of sync caused by noise or similar.
I can't unfortunately, it's a ZyXEL P660, and after it's been running about 12 hours
all the options apart from the status page vanish, it it requires a power cycle re-boot
to restore them.
So although I can remote log in to it, all I can see is the up/down sync speed, and no
other options. Less than optimum isn't it ?
BTW it's a 21CN exchange, if that might help or hinder things ?