Internal Network Speed Help

[Columbo]

So have recently moved into a new house about 2 months ago and struggling with the internal network setup.

I've got Sky Gigafast 900mbs and wired to the router speeds are rarely below 700mb at peak times so the speed coming into the property is fine.
It's when I try to get anything like those speeds on wireless where it starts to fall apart and more specifically my gaming PC location pictured below.

I've setup a TP Link Mesh system (X55 AX3000) and while the setup was easy, works and coverage is superb I'm only getting about 200mb max to Gaming PC.

Setup is as follows:
Node 1 is connected via Ethernet to the router
Node 2 is in the Kitchen downstairs
Node 3 is connected my PC via Ethernet upstairs

I know the Sky router is probably gash, but I dont wanna spend a chunk of cash on a router and achieve the same result.
Additionally I know hardwiring is the most reliable way but I dont want to start running long cables through mutiple walls so looking for some advice on the best approach.

 

[Columbo]

Thanks for the sugestions above guys, I'd not ruled out hard wiring as such I just didnt want put mutiple holes in floors / ceilings and walls to get the the cable run, however ChrisD has pointed out a really good solution I think and one I'd not even considered.
It is a brand new build yes and I can go up the stack directly into the loft, across and back down into the office room where I can just terminate with network port in the wall.

Looks like the best solution to me anyway.

For info I have also tried Powerline connestor which I used in my old house and used to get about 600mb, for some reason in this house I got between 90-120mb witht he same adaptors...weird!