ref the SNRM, my TT HG635 reports 2dB following a brief power cut (I think it's called a 'brown out', only dipped for half a second, but enough to reboot the router).

Before then, the TT DLM had fixed the SNRM at 6dB and my speed was around 12Mb/s

Since the reboot it's been steady at 2 or 2.1, the line is stable, and I've got the speed up to 13.3Mb/s

Also, regarding Interleaving; my previous routers (the HG533 and HG633) both said interleaving was on, but the 635 says it's off.

I had intended swapping the routers to see what they reported regarding the interleaving but since the DLM set the SNRM at 2dB I'm reluctant to play with them in case it goes back to 6dB.

OP, is your router the HG633 or the more recent D-Link 3782? My HG633 wasn't very reliable so I dropped it in favour of the older HG635.

In reply to a post by vitrocmax:

ref the SNRM, my TT HG635 reports 2dB following a brief power cut (I think it's called a 'brown out', only dipped for half a second, but enough to reboot the router).

Before then, the TT DLM had fixed the SNRM at 6dB and my speed was around 12Mb/s

Since the reboot it's been steady at 2 or 2.1, the line is stable, and I've got the speed up to 13.3Mb/s

Also, regarding Interleaving; my previous routers (the HG533 and HG633) both said interleaving was on, but the 635 says it's off.

I had intended swapping the routers to see what they reported regarding the interleaving but since the DLM set the SNRM at 2dB I'm reluctant to play with them in case it goes back to 6dB.

Default target margin appears to be 6dB on my TTB ADSL line - I set it to 3dB with a Billion 7800N router and now it only varies between 3.5dB and 4dB night and day. Last reboot was during daylight hours and the link time has been 46 days. BTW the 3dB margin setting survived previous reboots.

Regarding interleaving: every reboot has seen an interleaving depth of 64/8. Perhaps on your TT line interleaving may not be applied to every resync?

I've placed an order for the 8800NL R2 so hopefully it will give speeds as good as the old Plusnet router as well as much more control over the connection.

Billion 8800NL R2 arrived today. Extremely easy to set up and it is currently connected at 17136Kbps with attenuation of 32db and SNR of 3db. That'll do me given where we are in relation to the exchange. A good bit better than the TT HG633 router that never connected anything faster than 14Mb.

That's excellent - hope everything goes well with the Billion

3db noise margin is an option talktalk DLM can choose yes

I've set the SNR on the Billion router to 3 rather than auto and I'm now getting this

Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 0.3 10.5
Attenuation (dB) 32.0 18.1
Output Power (dBm) 0.0 12.7
Attainable Rate (Kbps) 19444 1160
Rate (Kbps) 18375 1019

The SNR has fluctuated between 0.2 and 0.5 and the uptime is 28 hrs so far so it seems to be doing a great job of holding on to the connection. Getting 18Mb from a line with 32.0db attenuation is very good indeed so I'm well pleased.

Just remember to keep the old talktalk one to plug in to diagnose faults. they flatly refused to diagnose any fault for me once until I went into the loft and got the old router out and plugged it in.