The WiFi reach of ISP provided routers isn't the best unfortunately. You could call Sky to discuss the WiFi max package and get a signal booster (doesn't boost the signal as such, just acts as a repeater to extend the WiFi range a bit). That is an extra charge per month though.
Other options are connecting via ethernet cable where you can and if not, using homeplugs are probably the next most reliable.
Not a sky broadband subscriber
