That's basically DLM helping you get a better speed. If you wait 10 days or so, (do not turn off your router). The line will find the perfect speed and stability.

I'm with BT Fibre 2 FTTC. I have exactly the same line attenuation at 16.9dB but I get
Data rate:19.781 Mbps / 77.242 Mbps
Maximum data rate:19.777 Mbps / 79.257 Mbps

This slightly dropped due to crosstalk. But I remember fully syncing at 80/20 2 years ago. Now it is down to 77Mbps and just a bit below the 20Mbps upload.

But I'm not going to complain too much as I'll soon be switching to Community Fibre which, of-course will be a much better service.

With the same line attenuation, I'd expect that you should fully sync 40/10, there's no reason why it should not!

Just make sure you never turn off your router. I'd also recommend that your land line phone is not plugged in as any ringing may cause it to drop connection and add noise to the line. An NTE5c master socket may also help improve your speeds.

Alternatively if you've got an Altnet FTTP coming your way I'd look into that as it is pretty much guaranteed to solve all the problems that FTTC carries.

In reply to a post by FTTCSux:

In reply to a post by j0hn83:

In reply to a post by FTTCSux:

Am I missing something - shouldn't I be getting faster speeds?

Your line is provisioned by Sky at 40/10 so it cannot go above that.
However the DLM has capped your line at 35/10 so you're getting a little less than what's possible.

Some migrations don't fully reset the DLM meaning banding can transfer from 1 provider to another but that's only for specific migrations and not usually the case.

It's possible the DLM has applied the banding since switching particularly if there was multiple resyncs from rebooting modems and moving the NTE etc.

You either need to wait for the DLM to remove the banding on its own (which isn't even guaranteed to happen or can take a long time) or convince Sky to perform a DLM reset.

The line looks like it might be interleaved due to the max rate being much higher than the sync speed but with only a 6.9dB SNRM.
Interleaving exaggerates the max data rate.

If the line is interleaved then I estimate you would sync around 38-39Mb/s if it wasn't capped by the DLM.

Thanks for the info. For clarity, I was with Sky on their Superfast (Not Superfast 35) and have moved to Onestream on their Fibre 55 package. My sync speed on Sky was always 34999 as I assumed this was the line capacity since moving in. Now on Onestream I realise that this might have been incorrectly capped by Sky as I'm now getting 8494 up and 37568 down, whilst the max rate today is 9954 up and 48423 down - much closer to the Openreach address check speeds.

As I mentioned if Sky decide your line can't support at least 59 Mbps (I think that's their threshold) they will have the line provisioned on 40/10 even when you order Superfast which is why you were seeing a capped speed.