80/20 slower than 40/10 on Plusnet

We're seeing a significant number of posts on the Plusnet community forums where users upgraded to 80/20 from 40/10 are seeing slower actual speeds.

Is this being seen on any other ISPs?

What were their actual speeds down and up on 40/10? Were they lower than (say) 36/7Mbps, or were they getting maximum?

Here's one topic where the 40/10 speed was 37.5/8.3

http://community.plus.net/forum/index.php/topic,1080...

Strange.

80/20 may be resulting in more cross talk and as more people order the drop off in speed is more than it used to be with ADSL.

Only way to be sure, is to have before and after bin plots from modems.

There is a possibility that the rush to order the 80Meg means that service is hitting some contention that the old 40Meg did not. Without access to fibre between cabinet and exchange, and the WBC network too it is impossible to say.

But only on Plusnet?

Is it though?

There was a slow down reported for BT Infinity that Ofcom noticed but written off as a HH3 issue, but that may have masked this issue.

I am not saying this is the reason for sure, but may account for some of it, or there is no single cause.

http://forums.thinkbroadband.com/plusnet/t/4161526-f...

In reply to a post by MrSaffron:

80/20 may be resulting in more cross talk and as more people order the drop off in speed is more than it used to be with ADSL.

But anyone on 40/10 is already running on Profile 17a - so the change to 80/20 shouldn't affect much? Unless it increases cross talk.

Don't think you meant to compare 80/20 with ADSL in that sentance.

Only way to be sure, is to have before and after bin plots from modems.

Sadly OR lock the modems

There is a possibility that the rush to order the 80Meg means that service is hitting some contention that the old 40Meg did not. Without access to fibre between cabinet and exchange, and the WBC network too it is impossible to say.

Yes, wouldn't be the first time an ISP has under estimated the amount of capacity they need from BT's WBC into their network.

so the change to 80/20 shouldn't affect much?

It will increase crosstalk, because the sync is capped, and so at sync time the bit loading is lower. Cue 17MHz pushing more bits into each bin and using more power, so more cross talk.

Not saying it is the total story, but may be a contributor.
On the locking I know, and it is becoming a pain to help understand issues and see through bluster and bluff from those who probably have no idea of the difference between 6dB and 12dB.