up high is key
you dont need line of sight to everything but you want the router to be not close to large lumps of metal or glass. the absolute worst location is often where an ISP installer puts it, on the foolr, downstairs, behind furniture.
if your router is not deigned to be wall mountable , put up a little shelf. I made a corner shelf based those glass/perspex things that folks buy for bathrooms.
for experimenting, you can get free apps for phone or tablets that show wifi strengh and speed , so you can go around the house measuring the signal, then go back & tweak router location - redo...
My virginmedia hub is made by Arris, and covers the whole house reasonably well from an upstairs central bedroom, but I added access points for fast streaming in specific locations. the 5Ghz band is best for speed but is worst for going thru walls and ceilings
here is vriginmedai video tips for best location:
https://www.virginmedia.com/help/get...fi-signal#hub3
wifi is not as efficient as wired but you should get about 50% of the advertised broadband speed over wifi with a well positioned router. e.g. I have 200Mbs wired, & I can get 100+ on wifi to a tablet from an access point in same room- which is way more than I actually need.