Should distance from the router be an issue?

[HowardRoyse]

Apparently all is well with the provision of broadband to my property. However my PC is on the top floor of my three-storey house and the signal is not great - download speed of 6mbs is not what I hoped for when rejoining Sky. 

Moving the PC is not an option, what else can be done?

[Mark39]

Power line adaptors may be a solution. 

Distance from the router, and obstructions along the route (walls; floors etc)  can absolutely be a problem for wifi.

[TimmyBGood]

@HowardRoyse 

Distance is absolutely an issue: all WiFi is zero Mbs on the other side of a few walls/floors or after some tens of meters of clear air.  You wouldn't want to share room space with a wireless router capable of blasting signal through building fabric without attenuation, and no amount of clever WiFi technology can override fundamental physics.