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[Edinburgh_lad]

Hello All

I have an extension connected to the socket. The router is connected to that extension.

When I put another DSL cable into the central filter of the master socket (this cable is not connected to anything; just a loose connection stretched out along where the extension cable), the line starts to behave in a different way:

1) With that other DSL cable:

- parts of the 'higher' spectrum disappear (anything between 2816 and 4096 if you look at the spectrum graph on a Fritzbox)
- the Central Exchange counter for Errors starts showing up errors, whereas the Fritzbox one isn't
- corrected DTUs significantly decrease to single digit figures
- min effective data rate displayed for the receive direction gradually reduces to effectively have only 128 kbit/s

2) Without that other DSL cable:

- parts of the 'higher' spectrum are there
- the Central Exchange counter shows '0' ES, whereas the Fritzbox one initially showed '5' ES's and stays like that
- corrected DTUs significantly increase to triple digit figures

Any ideas what is happening here? Thank you.

[burakkucat]

Any ideas what is happening here?

Yes. By plugging that cable into the data socket, on the SSFP at the master socket, you have created a bridging tap.

[licquorice]

..........and an aerial to pick up all sorts of interference.

[Weaver]

Do you get better performance when the router is plugged into the master socket directly?

[HPsauce]

Also, what is the nature of the extension, how is it connected and what sort of cabling?

[burakkucat]

Do you get better performance when the router is plugged into the master socket directly?

No because when moving the device from the extension socket back to the master socket the extension wiring will then be a bridging tap.

[meritez]

..........and an aerial to pick up all sorts of interference.

Is that why BBC Three is back on the telly?

[licquorice]

 

[Alex Atkin UK]

No because when moving the device from the extension socket back to the master socket the extension wiring will then be a bridging tap.

This just highlights why self-install was such a terrible idea.  There must be thousands of people with bridge taps, I know my friend had one when on Digital Region as I had to go and remove the ring wire, but I wasn't aware of bridge taps back then so that remained (but didn't impact his service seeing as we were the only two VDSL connections on the cabinet I suspect plus he was probably only ~100m line length).

[HPsauce]

Wikipedia has a half-decent description: https://en.wikipedia.org/wiki/Bridge_tap

I always worked (I'm long retired) on the basis of simplifying phone wiring to the extreme if broadband is involved.
Short and simple.

My home installation isn't perfect (phone-wise) for pragmatic reasons, but the router is on a 0.5m cable from the master socket.

[j0hn]

Short and simple.

My home installation isn't perfect (phone-wise) for pragmatic reasons, but the router is on a 0.5m cable from the master socket.

Same here, though I went a bit more extreme when I had FTTC.
25cm patch lead with the connector cut off at the master socket end with the (solid core not stranded!!) cable punched down directly to the IDC terminals inside the master socket.

https://ibb.co/S037bP5

[Edinburgh_lad]

Thank you all for your responses - much appreciated.

This just highlights why self-install was such a terrible idea.  There must be thousands of people with bridge taps, I know my friend had one when on Digital Region as I had to go and remove the ring wire, but I wasn't aware of bridge taps back then so that remained (but didn't impact his service seeing as we were the only two VDSL connections on the cabinet I suspect plus he was probably only ~100m line length).

Well, actually, it was a pure accident that I noticed what I described in my first post; it happened while I was disconnecting the extension. But thanks to this forum, I now know what happened. By the way, my Fritzbox also reported that there was a bridge tap (they called it split connection or something like that).

There was no impact of the bridge tap on our connection apart from what I described above.

In my case self-install isn't a terrible idea but done for pragmatic reasons so the router can be in the hallway while the master socket is the master bedroom; I'd hope that the extension is correctly connected. Certainly no OR engineer said it wasn't.

So, the wiring (unshielded twisted solid core cable) is connected to the 5C master socket (fixed part), while the bell wire is connected to the removable part of that same master socket (as we still have a retro GPO phone). All that to the extension socket which is ADSLNation filter. My understanding therefore is that unfiltered signal from 5C goes to the filtered box (ADSLNation), where it is filtered for the GPO phone and broadband.

[Alex Atkin UK]

So, the wiring (unshielded twisted solid core cable) is connected to the 5C master socket (fixed part), while the bell wire is connected to the removable part of that same master socket (as we still have a retro GPO phone). All that to the extension socket which is ADSLNation filter. My understanding therefore is that unfiltered signal from 5C goes to the filtered box (ADSLNation), where it is filtered for the GPO phone and broadband.

But that's my point, there must be a lot of properties without a filtered face plate.  Mine wouldn't have one if I hadn't fit it myself, the phone line pre-dates what we call a master socket today.

Anyone who never had an engineer out for a fault and had their phone line fitted pre-ADSL is unlikely to have the facility for a filtered face place, plus we've seen the utter nightmare of some flats with star wiring.

[HPsauce]

the wiring (unshielded twisted solid core cable) is connected to the 5C master socket (fixed part), while the bell wire is connected to the removable part of that same master socket (as we still have a retro GPO phone).

You can get rid of the bell wire entirely, and should. 
Just fit a plug-in broadband filter locally to the Retro phone (at the end of a 2-wire already-filtered extension) and it will recreate the bell signal for you when called.
Done it loads of times though I no longer have any phones that need it.
It's irrelevant to a phone if there are multiple filters in series. Not the same for broadband though. 

Test it first obviously, but in the past every single plug-in filter I used did that job fine.

[j0hn]

As above, I would disconnect the bell wire at both sockets and use a "rat tail" style broadband filter where the old phone is connected.

You may even notice an immediate improvement.