In reply to a post by RobertoS:

In reply to a post by Realalemadrid:

Noise margin reduction to 3dB has been happening on ADSL2+ for a long time, well before the FTTC version.

On BT Wholesale connections. Is Supanet on one, or is it LLU-based?

AAISP also allow 3db noise margin on TallkTalk based ADSL2+ lines:

3dB is now supported! As of November 2015 customers can request a 3dB profile. The process is a little long winded, but once a Support staff member picks up the task 3dB can be applied within a few minutes. Do contact us.

https://support.aa.net.uk/TalkTalk_Wholesale_Line_Pr...

As Realmadrid rightly says, if a BTw ADSL 2+ circuit is viewed by DLM as super stable, then it will tweak down to a 3db target .... has done so for many years.

Used to cause problems with Cisco modem/routers which (for reasons beyond my ken) would not sync on a 3db target .... though not seen this fault for a few years now.

In absence of any further posts from the OP I guess we'll never know. My opening reply was just a hunch based on a clearly very short line.

Fair enough. I knew ISPs could change the target SNR on ADSL but didn't realise DLM was setup to do it automatically - maybe it was after I moved to FTTC.

My point however being that realmadrid did not specify BTW circuits. Which on ADSL2+ are a minority of the connections. As opposed to FTTC where 100% are Openreach.

Still being pedantic, but that seems to be par for the course. Why did I need to specify BTW circuits, it was a general comment and nothing to do with all FTTC circuits being BTOR, also I wonder how you could prove it is for a minority of ADSL2+ circuits?

Edited by Realalemadrid (Wed 12-Jul-17 16:23:01)

In reply to a post by Zarjaz:

As Realmadrid rightly says, if a BTw ADSL 2+ circuit is viewed by DLM as super stable, then it will tweak down to a 3db target .... has done so for many years.

Used to cause problems with Cisco modem/routers which (for reasons beyond my ken) would not sync on a 3db target .... though not seen this fault for a few years now.

In absence of any further posts from the OP I guess we'll never know. My opening reply was just a hunch based on a clearly very short line.

What reading EXACTLY do you need from my router - a Netgear 3300 I think,
But thanks for all your replys, interesting.

That requires a manual intervention. BT does it automatically and if your line then becomes unstable it will revert to 6dB.

Sync rate, SNR, attenuation please.

ADSL Link Downstream Upstream
Connection Speed 24512 kbps 1022 kbps
Line Attenuation 14.5 db 6.8 db
Noise Margin 2.6 db 9.9 db

Zarjaz appears to have been correct. Your Noise Margin (SNR) at 2.6 suggests you are now on a stable connection with a 3dB target. If you monitor for a day or two you will see the 2.6 figure increase to 3dB or maybe a little more, then drop back down to 2,.6 or so. Then repeat on a 24 hour cycle!