Only way replacing copper that is between exchange and cabinet should have an effect is the voice side and injecting noise affecting the VDSL2 side from cabinet onwards, but that should be removed by the filtering at the cabinets

One option is that you have a joint pillar which is between the home and the actual cabinet, only way to know is to say which exchange and cabinet number, and someone will point Streetview at where the cabinet actually is.

Could this be a faulty VDSL Filter in the FTTC Cabinet, in combination with ADSL still being linked in the Telephone Exchange (E-side), thus the Modem in his house, is being offered two signals, ADSL from the Exchange and VDSL from the FTTC Cabinet?

In reply to a post by eckiedoo:

Could this be a faulty VDSL Filter in the FTTC Cabinet, . . .

Yes, a defective low-pass filter could possibly account for the symptoms so described.

Thanks for confirming that possibility.

When a subscriber upgrades from ADSL to VDSL, what is "normal practice" in the Exchange?

Is the ADSL feed in the Exchange left physically connected; or is it disconnected; or otherwise "switched OFF"?

Edited by deleted (Mon 20-Mar-17 07:20:16)

Sky modem/routers always try to establish a ADSL connection first before VDSL2. Guess it saves a bit of time just in case it's being used non-FTTC line.

Edited by simon194 (Mon 20-Mar-17 09:57:23)

That isn't what the log in the OP's second post shows.

Not only that, but when it does try ADSL it does so for one minute 31 seconds before giving up. If all Sky FTTC connections took getting on for two minutes to negotiate sync there would be screams all over the internet.

Edited by RobertoS (Mon 20-Mar-17 10:10:53)

You got it!

It is usually left connected, but port switched off, until such time as the port is required elsewhere.

In reply to a post by eckiedoo:

Is the ADSL feed in the Exchange left physically connected; or is it disconnected; or otherwise "switched OFF"?

The process of minimum intervention is followed. So the physical jumpering, connecting the exchange located MSAN to the circuit, is left in situ upon an end-user's upgrade from a G.992.5 to a G.993.2 based service. Obviously if that MSAN port is now required for a different end-user's service, the jumpers will be modified appropriately.

Hence it is quite possible for the G.992.5 signal to remain upon the circuit, event though a G.993.2 signal is now being injected at the cabinet. It really depends upon the "loosing" provider's mode of operation . . . if a change of service provider has also occurred.

The cabinet based low-pass filter will take care of the above scenario perfectly adequately.

The low-pass filter actually performs a number of functions:

(1) It prevents the E-side cabling acting as a bridge tap on the G.993.2, D-side based, circuit.
(2) It enables the voice-band signal (300 Hz to 3400 Hz, for telephony) to be extracted from/inserted into the G.993.2 circuit.
(3) It prevents any exchange based G.992.5 circuit, if still extant, from being extended to the end-users CPE.

Thanks for the detailed reply.

Assuming the Filter-Link in the right-hand side of an Huawei FTTC Cabinet becomes faulty, that appears to be one possible way of how ADSL signals appear on what should be VDSL-only.

However, the probability seems very low.