In reply to a post by Zarjaz:

I don't understand what typing of extension cabling can induce issues

The ‘alarm cable’ referred to is hideous stuff. All non twisted, multi strand.

looking at the picture, there was several cut cables, un twisted too. I don't know what David's fttp path is, but if he has a longish wait, it may be worth somebody to put a nte 5c (or latest equivalent) and do the extension wiring properly ..... As theres no effective test socket, he has zero chance of resolving his snr drop. Errorr'd seconds also means re-transmission and effectively lower bandwidth.

In reply to a post by Zarjaz:

It doesn't show CRCs but it shows errored seconds and severely errored seconds. In 20 hours of connection there's been one of each.

For me that rules out REIN being the cause.

If it's not REIN, does that rule out internal wiring issues? Or could the internal wiring still be picking up interference from equipment like a freezer etc?

In reply to a post by Taras:

looking at the picture, there was several cut cables, un twisted too. I don't know what David's fttp path is, but if he has a longish wait, it may be worth somebody to put a nte 5c (or latest equivalent) and do the extension wiring properly ..... As theres no effective test socket, he has zero chance of resolving his snr drop. Errorr'd seconds also means re-transmission and effectively lower bandwidth.

Yes, there appear to be unused 'strands' in the cable which has been put in that have been cut and just left, so it's created a bit of a spaghetti effect behind that plate.

I checked about FTTP and it says it'll be available before December 2026 - not sure if that date will keep getting pushed back or if it'll genuinely be in by then. Either way I think I'll get a local telephone engineer to put a proper master socket on and disconnect the extension altogether. I looked at getting BT to do it but it seems they don't really deal with stuff inside the house.

I reckon you need a visit from Openreach.

I see no alarm wire.

But would love to pull that wiring about and see what goes where. You might have a bridge tap causing issues.

In reply to a post by davidw87:

In reply to a post by Taras:

looking at the picture, there was several cut cables, un twisted too. I don't know what David's fttp path is, but if he has a longish wait, it may be worth somebody to put a nte 5c (or latest equivalent) and do the extension wiring properly ..... As theres no effective test socket, he has zero chance of resolving his snr drop. Errorr'd seconds also means re-transmission and effectively lower bandwidth.

Yes, there appear to be unused 'strands' in the cable which has been put in that have been cut and just left, so it's created a bit of a spaghetti effect behind that plate.

I checked about FTTP and it says it'll be available before December 2026 - not sure if that date will keep getting pushed back or if it'll genuinely be in by then. Either way I think I'll get a local telephone engineer to put a proper master socket on and disconnect the extension altogether. I looked at getting BT to do it but it seems they don't really deal with stuff inside the house.

You can get your isp to order a service from or to do so but it will be expensive. If you do know of a local telephone engineer then do get them to sort it out. At the very least hopefully your snr issue will be resolved and if theres any further issues you can test things via the test socket. You may get faster speeds (after a dlm reset)

[edited to remove a stupid question which was answered in david's opening post]

Edited by Taras (Tue 14-Jan-25 22:09:52)

In reply to a post by davidw87:

Is it likely then that the SNR margin dropping is due to interference on the internal wiring, rather than on the line coming into the house? I have an analogue phone plugged in but rarely use it. There's no noise on it though, even when I listened while the SNR had dropped.

I am becoming suspicious of your phone wiring, particularly as you have an analog phone in use.

In reply to a post by davidw87:

Here are two photos:

https://i.ibb.co/ckTyWgM/IMG-20250114-151403944.jpg
https://i.ibb.co/xLfghKL/IMG-20250114-151536625.jpg

The top plate covers where the (underground) phone line comes into the house. Behind this is where the extension lead (off to the left) is connected and runs about 10 metres around the room to a socket on a wall which looks like a BT master socket.

Also connected is a short cable going to the bottom socket, but it terminates in the socket and isn't connected, so the socket is dead.

The connections behind the top plate seem to be made using some sort of transparent connector. None of it looks good to me!

OK, that looks a mess. You need a faceplate filter somewhere in the installation. An NTE5c as suggested by Taras. Can you tell us where your router is plugged in? And what filters are you using?

Looking at the arrangement, it seems a fair bet that the incomer is fed to the lower socket, either in parallel with the circuit going to the left, or the circuit goes into the lower socket and doubles back in the same cable. Either way, this is asking for problems. There also appears to be a cable coming out from the bottom of the lower socket.

OK, the rules for sorting the wiring

• You need a straight run from the incomer to an NTE5c. No parallel connections, no intermediate sockets
• All your phone sockets for phones must be connected to the voice side of the NTE5c
• Your router must be connected to the data side of the NTE5c. You can have an extension to the router, in which case you must run the router on the extension, not on the NTE5c. No parallel paths or other sockets on this data extension

Once you have wiring compliant with these STRICT guidelines [they are not rules LOL], I would hope you see an improvement. But it is not worth mains conditioners, other counter measures or even any investigation until the wiring is compliant. By all means try a temporary lash up of just a single cable to a NTE5c [ie compliant with the guidelines above] and plug your router in to see what works with no analog phone wiring.

Hope that helps.

In reply to a post by Zarjaz:

I reckon you need a visit from Openreach.

Do you think the issue's more likely external or internal? Or too difficult to say?

In reply to a post by Taras:

What are your stats on your modem router?

Here's a screenshot of the stats, taken just now: https://i.postimg.cc/bJgDWFnt/Screenshot-from-2025-0...

That's after about 26 hours of connection so far. Checking the logs that the Raspberry Pi's been keeping shows no drop in SNR today or last night.

Will be interesting to see what happens in the coming days given the Pi's shown a drop in SNR roughly every 2-3 days over the last 10 days (and the two last night were bad enough to cause the resyncs).

Just in case the router was at fault, I reset it to factory settings yesterday evening (straight before the current connection was made) and restored my own config. It's been running for about 3 years (though has been rebooted a few times a year) so I don't know if a fault had developed that may now have been flushed out. I'm not sure if a router itself could cause a drop in SNR though.

In reply to a post by DFScale:

No parallel connections, no intermediate sockets

from the first image thats what comes to mind that the router and phones are running in parallel, all you would need an untwisted pair in that pathway and that may cause problems ..

The drop cable (or external cable from a BT66 external junction box?) connected directly to the back of a NTE5 master socket fitted with a filtered faceplate, CW138 cable (or CAT5e) connected to the A&B terminals on the filtered faceplate to a RJ11 socket (effectively a "data extension") might be a good solution. Router would be connected to the RJ11 socket and a phone connected to the front of the filtered NTE5 master if that is convenient.

Good luck.

Edited by 4M2 (Tue 14-Jan-25 22:37:34)

you have g.imp and interleave on at 4. The thing is you are asking if its internal or external in regards to the issue, with the current wiring you can't actually test if it is internal.

do you have any micro-filters on any part of the wiring (as per dfscale's question)?

Yes the OP needs a NTE5 for testing, i.e. a test socket directly from the external feed.