topic Re: Permanent increase to downstream SNR on FTTC in Broadband

Permanent increase to downstream SNR on FTTC

dleholt — Thu, 27 Feb 2025 11:22:31 GMT

I’ve an ongoing issue with stability on my line. A few years back we had multiple OpenReach engineers come out and eventually they agreed that as we are quite some distance from the cabinet, it’d be hard to maintain a connection with a downstream SNR of 3dB, and with a quick phone call they were able to get it set to 6dB.

For 2 years the line was rock solid, until just before Christmas I noticed we were getting multiple dropouts per day, and checking the router logs I could see it was syncing with ~3dB again.

I’ve since made quite a few calls to PlusNet, mostly without any success until last time they did say they could do something to get the SNR increased and sure enough, within a couple of minutes my router reconnected with 6dB. All was well for a few weeks but now I can see it dropped connection a few days ago, resynced at 3dB again, and is once again unstable.

Does anyone know whether PlusNet are actually capable of getting this changed permanently? Or do I need to insist on another OpenReach engineer visit and persuade them to do it? I’m also wondering whether I can buy my own router that allows me to set this myself?

Re: Permanent increase to downstream SNR on FTTC

outcast — Thu, 27 Feb 2025 11:30:55 GMT

Ask Plusnet to change the "stability profile" of your line to a more stable setting ?.

Rather than repeat what I've written about this, look at this post where I describe the various settings.

Re: Permanent increase to downstream SNR on FTTC

dleholt — Thu, 27 Feb 2025 12:21:59 GMT

Thanks, I think that’s one of the things they did, but it made no difference. I think the problem here is that it’s not just a short term issue with the line. It was https://community.plus.net/t5/Broadband/Multiple-disconnects-every-day/m-p/1897493#M352693 from a few years ago where it was suggested we’re too far from the cabinet to maintain a stable connection at 3dB.

It sounds as though PlusNet can’t request this themselves though and I’ll need to get an OpenReach engineer out again. Or try to find a router/modem that lets me set a higher SNR.

Re: Permanent increase to downstream SNR on FTTC

outcast — Thu, 27 Feb 2025 12:49:56 GMT

@dleholt wrote:

It sounds as though PlusNet can’t request this themselves though and I’ll need to get an OpenReach engineer out

Plusnet can order an alteration in 'stability profile', and the change usually gets applied within a day - without engineer visit.

@dleholt wrote:

I think that’s one of the things they did, but it made no difference.

Perhaps a member of Plusnet staff can check what your current 'stability profile' is set to ?

Re: Permanent increase to downstream SNR on FTTC

Windings — Thu, 27 Feb 2025 14:45:00 GMT

@dleholt @outcast Checked into the account in question and the stability profile is 100% set to stable and not the standard profile. The stability order was placed back on 16/01/2025 and will have taken a couple days to take effect but its definitely there.

Being able to set your own SNR margins from your router isn't possible as far as I'm aware, I do know that there are certain modems out there that have 'router stats' settings which let you adjust your target SNR margins. I have however requested for your SNR margin to be changed back to 6db. I will stress that this request isn't always accepted as it has to go through Openreach and if their recent DLM health management has shown inconsistencies and stability issues at 6db, the submission will get rejected.

Hopefully I've been somewhat helpful here.

All the best

Re: Permanent increase to downstream SNR on FTTC

dleholt — Thu, 27 Feb 2025 14:57:00 GMT

Thanks, Joe! I think this is what you guys did on my last support call too, and I was told it might get rejected but the router almost immediately dropped and reconnected with a 6dB margin. Fingers crossed it sticks this time!

Re: Permanent increase to downstream SNR on FTTC

outcast — Thu, 27 Feb 2025 16:31:24 GMT

@dleholt wrote:

Fingers crossed it sticks this time!

If it doesn't, you could try a better external modem as Joe suggested, or reconsider this -

@dleholt wrote:

At this stage I’m starting to wonder whether a switch to newly laid Swish Fibre FTTP

It would be worth checking if you can get CityFibre as the prices are usually lower than Swish

and you can choose from a variety of ISPs instead of being trapped with only Cuckoo supplying Swish FTTP.

Re: Permanent increase to downstream SNR on FTTC

dleholt — Thu, 27 Feb 2025 17:08:16 GMT

Hehe, Swish is still not up and running here. I think they must have given up. BT plan FTTP by the end of 2026 though. A lot of houses in the road have gone to satellite.

I tried various modems a few years back but all of them would drop a few times a day to some degree. The most stable was my original OpenReach modem but that requires two boxes. A BT business SmartHub reconfigured for PlusNet was ok, certainly better than the Hub One. The Hub Two’s been ok too with a 6dB SNR and has far better wifi coverage.

Re: Permanent increase to downstream SNR on FTTC

dleholt — Fri, 28 Feb 2025 13:25:57 GMT

So far 2 random disconnects since yesterday afternoon and unfortunately it‘s still set to 3dB.

Re: Permanent increase to downstream SNR on FTTC

Windings — Fri, 28 Feb 2025 17:30:48 GMT

@dleholt It would seem that Openreach rejected my request for the SNR margin change

I will attempt another request but if i get no joy from it, you would perhaps have to look into a suitable modem that allows you to edit your SNR margins that way.

All the best

Re: Permanent increase to downstream SNR on FTTC

dleholt — Fri, 28 Feb 2025 18:13:36 GMT

Thanks for trying Joe. Is it worth arranging an engineer’s visit again? That’s what it took last time.

Re: Permanent increase to downstream SNR on FTTC

RealAleMadrid — Fri, 28 Feb 2025 20:10:41 GMT

@dleholt The Openreach DLM system does not allow a fixed SNRM to be set by any method. I would advise you not to try and use a router that will allow tweaking of the SNRM, it is very unlikely that it will work.

Re: Permanent increase to downstream SNR on FTTC

outcast — Fri, 28 Feb 2025 20:26:52 GMT

Why is that then ?.

I've managed my tweaked SNRM for at least 19 years, as my line's margin varies with the seasons.

In the winter months I increase the margin to prevent during the evening it fading to zero and dropping out,

and in the summer I reduce the margin to optimise for speed.

It works perfectly ! - both on ADSL and VDSL.

Re: Permanent increase to downstream SNR on FTTC

dleholt — Fri, 28 Feb 2025 20:49:18 GMT

They can definitely change it on their end. Last time it took about 3 or 4 engineer visits before one finally confirmed they could increase SNR and made a phone call to get it increased to 6dB. That lasted about 2 years until just before Christmas it dropped back to 3dB and now the line is unstable again.

Re: Permanent increase to downstream SNR on FTTC

dleholt — Fri, 28 Feb 2025 20:52:20 GMT

@outcast what router do you have, if you don’t mind me asking? I’m so out of date with these things that I don’t know what to look for.

Re: Permanent increase to downstream SNR on FTTC

outcast — Fri, 28 Feb 2025 21:10:41 GMT

@dleholt wrote:

@outcast what router do you have,

My router is pfSense firewall software running on an Intel J3455 CPU Gigabyte motherboard with two Ethernet ports.

I have always used separate external modems.

For a modem with adjustable SNRM for VDSL, my recommendation would be a DrayTek Vigor 130

or for the most awesome VDSL modem (without adjustable SNRM) then the DrayTek Vigor 167 is hard to beat.

You should be able to get either of those (second hand but like new) for £20 to £30 on eBay.

You should be able to connect either of those modems to the WAN port on your Hub-2

Re: Permanent increase to downstream SNR on FTTC

Townman — Sun, 02 Mar 2025 08:59:07 GMT

The question which needs to be asked and answered is why if the line is unstable why will the BT system not allow a 6dB (or higher) target SNRM to be set to deliver improved stability?

Is the order being rejected for some other reason?

Re: Permanent increase to downstream SNR on FTTC

LexLex2020 — Sun, 02 Mar 2025 10:13:45 GMT

For any products past ADSL, (FTTC, SOGEA) Manually changing the SNR margins through BTWholesale just gets rejected right away. It's only use is for ADSL Lines.

It would be ideal if we could, as far as I am aware they simply just get rejected unless it is an ADSL line.

Not sure the exact reason for this, but yeah, just a no go sadly.

Re: Permanent increase to downstream SNR on FTTC

outcast — Sun, 02 Mar 2025 12:47:14 GMT

@dleholt wrote:

I can’t hear any noise on the phone, although I’m unable to do the proper quiet line test given I only have an old pulse dial telephone (yes, really!) and hence can’t select the option. The Hub Two (and phone) are plugged directly into the master socket fitted with a faceplate filter.

How far away from the Master Socket is the telephone ?
How far away from the Master Socket is the Hub Two ?
Is there any house telephone extension wiring attached to the back (inside) of the removable filtered faceplate ?
Have you tried plugging the Hub Two into the TEST socket (behind the filtered faceplate) ?
Do you use any 'powerline' adaptors to extend your LAN around your home ?
Is there any other electronics or electrical equipment near to your Master Socket ?

Given that you're on FTTC broadband, and that the UK PSTN landline telephone system will be decommissioned from the end of 2025, have you considered 'upgrading' your phone service to VoIP (phone calls via broadband) ?.

You will probably save money by 'upgrading' your Plusnet FTTC (VDSL and phone) contract to SoGEA (VDSL without phone) and then migrating the landline number to VoIP, and if you want to carry on using your landline phone from 2026 you will have to 'upgrade' in the coming months anyway !.

On my home setup, I had as near perfect broadband and phone wiring as it was possible to achieve, but when I finally changed my line from FTTC to SoGEA, my modem's maximum achievable sync speeds immediately improved, and the frequency of modem dropouts pretty much disappeared.

You can still use your old pulse dial phone with a VoIP service if you use an appropriate adaptor to connect the phone to a LAN port on your router, there are several instructional videos on YouTube of how to achieve that, for example -

YouTube : How to use rotary phones with VoIP

YouTube : How I Connected A Rotary Phone To VoIP Phone System

Re: Permanent increase to downstream SNR on FTTC

Townman — Sun, 02 Mar 2025 14:14:35 GMT

@LexLex2020 wrote:

For any products past ADSL, (FTTC, SOGEA) Manually changing the SNR margins through BTWholesale just gets rejected right away. It's only use is for ADSL Lines.

Hi Lex,

Thank you for the clarification / knowledge share.

So if that mechanism cannot be used on FTTC / SOGEA, are there other leavers / buttons to be pulled / pushed in circumstances where a sticky DLM configuration is leading to poor stability? Is this where line profile (stable / standard / speed) comes into play?

Surely BTw must have a vector for managing this space?