All modems are now up and running.
A bit of a disaster, I suddenly lost 120k of downstream on line cwcc@a.1, the first-installed ZyXEL, which had been in use for a couple of weeks. Mrs Weaver accidentally pulled the phone cable out of the wall. When it came back up that's when it decided on the lower sync rate. I rebooted the modem, and that only made things very slightly worse.
Have I merely upset BT’s DLM? If so how do I get my 120k back? Would a target SNR margin reset help? I can force one using clueless.aa.net.uk controls.
That was before the other two new ZyXELs were plugged in so I’m hoping that it’s nothing to do with the presence of those other modems. I can’t see how that would be possible anyway?
As for the other two lines:
line cwcc@a.3 : +155k downstream sync rate, 2706 to 2861 kbps. Upstream +4 kbps, 436k to 440kbps
line cwcc@a.4 : +22k downstream sync rate, 2830 to 2854kbps. Upstream -66 kbps [!], 496k to 430 kbps
The loss of 13% upstream on line cwcc@a.4 is really bad news and a similar loss of ~50k happened on changing modem model on line cwcc@a.1 originally. So I have now lost 176k upstream in total or around 10%. Not good at all, dry disappointing. An expensive price to pay for a bit more upstream.
If I get line cwcc@a.1 back to where it was before this morning’s nasty accident, then I will have gained ~ +290 kbps approximately in total downstream sync rate combined across all three modems.
Perhaps I will try the reset to see if I can get my missing 120k back?