AIUI for DIY Cat 5 is better than the Data Extension Kit, but I could be wrong. The DEK is better than standard BT extension wiring I think though.

These days it is hard-wired to the master, but where and how depends on where they fit the VDSL2 filter plate. If that is at the original master then it goes to unfiltered IDC connectors on the back of the VDSL plate, just like the old filtered master faceplates wanting an unfiltered extension. I think the engineers then fit just a DSL socket at the remote end.

Once they depart from the standard, various things happen depending on what the user wants and they agree to do.

I think you are meaning they should ask the engineer just to leave the cable for you to run later?

Engineer turned up a day early and because the FTTC cab is literally within 50 metres, said that he could swap the master/extn without any real impact to the line speed.

This was done and there is no impact.

Thanks for all your help.

Brilliant . Yes - if that close there is no problem.