Hi WiFi hub is currently connected to phone port by small adapter, lead from attic to phone port is about 12metres in length and at leat 15/16 years old recently done hall up and was wondering if shortening the cable and placing the hub at the top of the stairs would improve WiFi in the house or should I get cable replaced?
Why would you need to replace the cable, wires don't wear out with age. Until you try it, you won't know if coverage will be improved, every situation is unique.
Will the age of the wire not affect the speed of the internet?
No