Vertical coverage problems

Our SoHo business is in a small cottage type house, barely 1,800 sq.ft. Problem is it is 3 floors. (Basement, main floor and attic space)  Our coverage for the third floor (attic) is slowly getting worse. 
Our neiborhood is very congested WiFi wise...

Our base unit is in the basement, all the way to one side...

the Attic station is as far to the other side of the house as we can put it.

verticle distance is about 30', Horizontal distance is about 60'.

we have routine drop outs, and then it will clock in at 150Meg...

My partner is begging me to run a hardline.

I need some help, ideas, suggestions, something....

The  diagnostics available on the Orbi are nonexistent, and Netgear is useless for support.  I am very close to tossing it out and trying something new that has support, or at least some diagnostics...