topic Re: Line speed in Broadband

Line speed

JHarland — Sat, 02 Aug 2025 12:31:50 GMT

I've had a new line put in for Plusnet FTTC, I can see DLM made a positive bump in download sync speed going from 50 to 53 and lowering noise margin. Before the bump my real world speed was approx 47 due to overheads etc. This morning my real world speed is still 47 despite the change in modem sync. This points to a mismatch between the reported sync speed and my ip profile or account profile at Plusnet? I've looked online and people talk about being able to see your line speed on your Plusnet account, I can't find this option anywhere, can someone point me to it? If that option is outdated and doesn't exist on the account I'm assuming that over time Plusnet will pick up on the increased bump in sync speed?

Re: Line speed

MisterW — Sat, 02 Aug 2025 12:47:07 GMT

This points to a mismatch between the reported sync speed and my ip profile or account profile at Plusnet? I've looked online and people talk about being able to see your line speed on your Plusnet account, I can't find this option anywhere, can someone point me to it? If that option is outdated and doesn't exist on the account I'm assuming that over time Plusnet will pick up on the increased bump in sync speed?

The Plusnet profile (Current line speed) is no longer used on the majority of connections, it only exists now on accounts with a static IP. There is still a BT IP Profile and it could well be that hasn't caught up with the change in sync speed.

Re: Line speed

outcast — Sat, 02 Aug 2025 12:51:36 GMT

@JHarland wrote:

I've had a new line put in for Plusnet FTTC

Does that imply that this is a new Plusnet account, or a line upgrade to an existing account ?.

I ask, because Plusnet run two routes through their network, "high touch" and "low touch".

The "current line speed" you are looking for is associated with the "high touch" network.

"high touch" is typically for legacy accounts, or those that have a static WAN IP address (before they became unavailable).

Most customers, have a dynamic WAN IP address, and are on the "low touch" network, so "current line speed" doesn't apply.

Therefore if your new line is on account that was started in since 18-Dec-2024, then you'll be on a dynamic address.

Re: Line speed

JHarland — Sat, 02 Aug 2025 12:54:02 GMT

It's an old account (since may) but I was having disconnects and the attenuation would go crazy high and noise margin drop to 0. Openreach came out in the week and hooked me up to a new physical copper line

Re: Line speed

Baldrick1 — Sat, 02 Aug 2025 13:03:02 GMT

Static IPs have not been available since the end of last year.

Re: Line speed

JHarland — Sat, 02 Aug 2025 13:19:42 GMT

I'm assuming over the next few days it will catch up and reflect my increase in sync speed, my download noise margin is only at 5.1 so I'm hopeful the line stays stable and it drops to the max target of 3 with a corresponding increase in download sync speed. Roll on full fibre being available in my area....😂

Re: Line speed

outcast — Sat, 02 Aug 2025 13:20:48 GMT

@JHarland it could be that the slightly faster re-sync rate was coincident with increased depth interleaving, which due to the increased transmission overheads, could mean that your real world (speed test) bandwidth remains about the same.

On my FTTC connection, my modem either syncs around 76Mbps on FASTPATH (no interleaving), or 80Mbps with interleave depth of 8, but the IP profile and therefore the useable bandwidth is more or less in the same ballpark.

Re: Line speed

JHarland — Sat, 02 Aug 2025 13:34:55 GMT

That is a possibility as I have noticed a slight increase in ping? Before the higher sync point was approximately 8ms my nearest speedtest server, now it's consistently 11/12, that would fit with increased interleaving depth?

Re: Line speed

outcast — Sat, 02 Aug 2025 13:37:39 GMT

Yes, increased interleave depth, does typically raise ping latency by a few ms with each step (1, 8, 16, etc).

@JHarland wrote:

I'm assuming over the next few days it will catch up

No, if you have only had the account since May 2025, then there is nothing to catch up, your line is what it is.

FWIW, for the 17 years I was on Plusnet ADSL and FTTC, with as static IP via the "high touch" routing,

my "current line speed" was always quick to drop to a lower speed due to short term poor weather conditions,

but NEVER 'updated' to a higher speed when the DLM sync speed recovered - I ALWAYS had to get staff to manually update it.

@JHarland wrote:

Roll on full fibre being available in my area....😂

Same here, fortunately for me on Wednesday, Openreach closed a nearby road for a week, while they lay new FTTP ducting cables under the carriageway, I also received an email notification from Openreach saying that they are now building in my area.

Re: Line speed

JHarland — Sat, 02 Aug 2025 13:45:59 GMT

Lucky you! My post code has recently updated on the openreach availability checker from "before December 2026" to "coming in the next year" so that's progress!?

Re: Line speed

JHarland — Sat, 02 Aug 2025 13:46:52 GMT

How did you get staff to update it? Just phone in and ask for the profile to be refreshed to match the modem sync speed?

Re: Line speed

outcast — Sat, 02 Aug 2025 13:54:07 GMT

I used to send a 'Private Message' via this forum to staff members who I knew would be sympathetic to my request,

and include a screenshot of the BTW IP Profile to substantiate my request, unfortunately that is no longer available !.

Other customers on here have said that they had success with "current line speed" updates by phoning in to Plusnet support.

Re: Line speed

outcast — Sat, 02 Aug 2025 13:55:39 GMT

@JHarland wrote:

Roll on full fibre being available in my area....😂

Have you signed up to receive Openreach build notifications for your address ?

Go to - https://www.openreach.com/fibre-broadband

Enter your postcode and address, then [Check Availability]

on the result page in the 'Full Fibre Broadband' box, click on the [Keep Me Updated] button, and provide your email info.

Re: Line speed

JHarland — Sat, 02 Aug 2025 14:24:02 GMT

I'll wait to see out the full DLM observation period as I would expect the noise margin to drop to 3 and the sync speed to increase further, once it hits that I'll contact Plusnet and get them to refresh the profile their end, saves me contacting them a number of times

Re: Line speed

outcast — Sat, 02 Aug 2025 18:44:40 GMT

@JHarland wrote:

I'll wait to see out the full DLM observation period as I would expect the noise margin to drop to 3 ...

If you're doing that, perhaps post here a screen shot of your router's line stats,

for what it looks like today, and again after 10 days of DLM settling time.

I believe the screen you are looking for has this header -

Re: Line speed

JHarland — Sat, 02 Aug 2025 20:26:59 GMT

These are my current stats, I get 48ish down and 8 up

Re: Line speed

outcast — Sat, 02 Aug 2025 21:28:50 GMT

Looking at that, I wouldn't anticipate any further lowering of your SNR or improvement in your download speeds due to DLM training, unless there is anything you can do to reduce the noticeable interference on the inbound VDSL signals.

Try unscrewing your BT Master socket faceplate, and connecting your router to the hidden "TEST" socket, and see whether your line stats are any better (preferably using the shortest DSL cable you have).

To connect your router's DSL socket to the TEST socket, you'll either need -

- an RJ11 to BT431 (phone plug) cable (possibly from an unused phone handset/base) -

- or use an inline dangly DSL filter to act as an adaptor for your RJ11 to RJ11 cable -

Re: Line speed

JHarland — Sat, 02 Aug 2025 21:42:37 GMT

Thanks for the tips but this is already plugged directly into the test socket to remove any internal wiring, I've bought a twisted pair rj11 cable and this microfilter https://www.run-it-direct.co.uk/adsl-vdsl-filters/vdsl-microfilter/ which was the best VDSL one I could find! I would say that my attenuation stats were similar on my old line and that did manage to get down to 3 noise margin and sync at 60, it stayed like that for a couple of months before the line started failing so I was hopeful this could get to 60 as well. Any more tips I can try I would definitely give a go!

Re: Line speed

JHarland — Sat, 02 Aug 2025 21:49:46 GMT

I do have an ADSLnation xf-1e microfilter that I know used to be the best for ADSL connections but I've not tried it with VDSL, it might be worth me giving that a go but I don't want to upset DLM by disconnecting etc

Re: Line speed

outcast — Sat, 02 Aug 2025 22:33:06 GMT

As you are already plugged in to the TEST socket, don't bother with changing the filters over.

The use of the filter in your case, is just to act as a RJ11 to BT431 plug converter, the 'filter' part is irrelevant.

Inside the filter, the BT plug and the DSL (MODEM) socket are directly connected together, with the noise filter only on the PHONE socket.

See this simplified circuit -

On my setup, I don't use any filter, I have a 50cm RJ11 to BT431 modem cable made with twisted CAT5e.