First a description of the layout.

Old stables extensively modernised along clean minimalist lines.  BT smarthub/ switch in cupboard at one side of the house; not sensible but we have to live with that, as security system is also linked in, ie not cost effective to change location.

We can get the RE365 to repeat wifi signal on side of house with the router, but zilch on the opposite side - I suspect with obvious copious loads of stud work, they may have used foilbacked board, thus maing it impossible to use repeaters.

We also tried  powerline adapters, without success, electical circuits are probably separated (historical?).

Access point could only be used if we could thread a cable through somehow, with current architecture/minimalist design, they are unlikely to tolerate trailing wires.

So question for the community,, any ideas how we could overcome these obstacles?