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upload upgrade has resulted in lower download speed

Posts: 24
Thanks: 7
Registered: ‎18-05-2016

upload upgrade has resulted in lower download speed


Plusnet user name:[Removed]

A few months ago my download SNR margin dropped from about 6db down to about 3.5db which I presume was due to a profile change by BT Openreach or Plusnet to allow customers get higher sync rates. I didn't ask for that change but was happy as the resulting sync speed increased to about 31mbps with a speed test result of about 27.7mbps. Everything was OK with that profile with no stability problems. Previously on the 6db SNR profile for downsream I was getting a download speed of about 21mbps.

As is the case for many customers I've now been given a free upgrade of the upload rate which was previously at a max of 2mbps and now from this morning I get an upload sync rate of 4.6mbps which is an improvement but isn't really needed or impressive.

The downstream sync rate is now 23596 kbps with a SNR margin of 6.9db. Line attenuation is 25.4 db.

Would someone please have my downstream SNR target put back to 3db as it was before the upload upgrade so that I may once again have the higher download rates.

Moderator's note by Mike (Mav): Personal information removed from a public forum to an area that staff can see.


Posts: 6,913
Thanks: 964
Fixes: 58
Registered: ‎30-07-2007

Re: upload upgrade has resulted in lower download speed

AFAIK ISPs have no control over the DLM and SNR targets. I suspect that the DLM settings will have reverted back to the default 6db targets when the regrade (to 40/10) order was processed. Since the DLM decided in the past that your line was stable enough to apply the 3db downstream profile, it SHOULD given time, reapply that...

Rising Star
Posts: 126
Thanks: 19
Registered: ‎01-05-2009

Re: upload upgrade has resulted in lower download speed

As MisterW has has correctly advised, PN can not control or adjust SNRM on VDSL (fibre) service, it's all down to BTW DLM action.

The re-banding upgrade from 40/2 to 40/10 would likely have involved a DLM reset, to what level I don't know (see kitz forum for more details on this) at least the DS SNRM target would be reset to default value of 6dB, DS G.Inp (assuming that's available on your line/cabinet) possibly de-activated and DS interleaving action/depth possibly changed, any or all of these will certainly effect your DS synch rate & data throughput speed.

Again, as MisterW has advised, DLM action should over time re-evaluate your line and eventually return it to DS pre-upgrade settings, my advise would be, don't interfere (that could possibly upset DLM) just be patient and give the system time to work.

Don't know what your router/modem set up is, but if you are in a position to drop your PPP session without loosing DSLAM synch, ie., don't switch off or unplug the DSL connection to the router, then this sometime helps to force an IP profile update which certainly can get stuck, this method won't upset DLM as synch is still maintained.

Good to hear that the PN US upgrades are progressing, I'am still waiting patiently on mine !