Permanent increase to downstream SNR on FTTC

[#1]

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?

[#2]

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.

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[#3]

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. 

[#4]

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@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.

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@dleholt wrote:

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

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

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[#5]

@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

[#6]

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!

[#7]

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@dleholt wrote:

Fingers crossed it sticks this time!

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

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@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.

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[#8]

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.

[#9]

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

[#10]

@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 

[#11]

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

[#12]

@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.