New Build House. FTP in cupboard + Metal stud walls Best setup?

I recently moved to a smaller house (circa 1100 sq ft) and bought my Netgear Orbi with me.

The house is new build and as BT Fibre to property (Good) and also has 4 pre-wired ethernet sockets around the house (Very good). What is not so good though is that the cabinet and input for all 4 ethernets is in an under stairs cupboard which is not the ideal place for a router of course. This means that if I want to use the pre-wired ethernet then the router needs to be in the cupboard to feed the inputs. On top of this the internal walls are metal stud walls.

I originally had an Orbi RBK50 which did not really work, you cannot switch wifi off an any of them so the main unit was boxed in under the stairs with a reduced signal but not reduced enough to have devices switch to one of the others. In the end I purchased a nighthawk AX8 which should be easily powerful enough for my house and it is however upstairs I am seeing a drop off in signal and speed. It works ok, is just not ideal and is bugging me. I put an ASUS router under the stairs with the wifi switched off which takes the inbound connectiona and feeds the ethernets. The Nighthawk in AP mode has been mostly in position 1 on the attached but I recently gave it a try in position 3 and it did not really improve things

Not sure what to do? Mesh with wireless backhaul seems pointless due to the metal walls and I cannot go mesh with wired backhaul without putting one of the nodes in the cupboard?

Any ideas much appreciated, happy to spend some money to get it right.

Shouldn’t this be planned right from the beginning of the construction? When I was getting my house plan made, I made a specific request to the company to make a place for Ethernet cables in the walls.
I already knew where I would install all the devices, and the company https://www.boutiquehomeplans.com/the-process helped me determine where I wanted the Ethernet cables to show up from the wall. In some months, the house was ready, and all the cables were exactly where I wanted them to be, so I did not have any issues with installing or placing all the devices. I think this is the best way to get this job done.