How far away is the router from the PC?
My set-up is, (bit of 3d imagination needed here), enter hallway, BT homehub is at ceiling height on left. Door to left is lounge c. 4x4 metres, door to right is kitchen/diner, c. 4x4 m. Ahead are stairs, leading left to right, to bed no 2, c. 4x4 m, above kitchen, with passageway above hall to bedroom 1, c.4x4m. All interior walls are wood/plasterboard, as are floors and ceilings.
Can pick up broadband anywhere downstairs, but can be a bit less reliable upstairs. May have to leave doors open, and not obstruct the signal with bodies (not dead, or piled up in mounds)..
PC on landing (music with 1.5 tb drive) is connected through ceiling with a cable to homehub, and then picked up wirelessly by laptop virtually anywhere.
Hope this helps..