telephone socket for Fiber need to use extension for DSL cable....

[#1]

just moved into new house, setting up all the routers ready for when plusnet activate my line here on the 18th and i notice the socket box is different from my old one. in the old one the DSL cable would plug directly into the socket box but on this one i have to use one of those old extensions..

Would i get the high fiber speed  with it like this or do i need to get the socket box changed so the DSL cable plugs in directly to socket box?

[#2]

It will work but for the best results get one of these  https://www.amazon.co.uk/LINDY-75114-VDSL2-Microfilter-Faceplate/dp/B014E4FIJK

You just undo the two screws, unplug the old one and plug this in its place.

[#3]

In addition to the above.

One thing jumps out - you've put the DSL cable into the router and not the modem

Also, don't leave the modem or router on the floor, they need decent airflow and if you put the router in a window, cover the rear of the routers details as anyone walking by can get free wifi (assuming the router is set as per the defaults).

[#4]

Extensions aren't ideal for a fibre connection so if possible I'd leave the modem on a short cable near the socket and then use a longer network cable or powerline adapters to situate the router nearer to where you'll be likely to connect wireless devices to it.