Bit of a strange problem. My sister's laptop suddenly stopped connecting to her router via wifi. Nothing has been changed on either the laptop or the router for over 6 months. The router seems fine - phones, tablet and a PC are connecting with no problem. Brought the laptop to my house and it won't connect to my wifi either. After doing diagnostics, tests etc we took the laptop back to PC World and it connected ok to their wifi!! They couldn't explain it and suggested doing a factory reset, which I did, but it still won't connect to either network. The only common factor is we both have Plusnet. So I'm at a loss to explain how the laptop can connect to PC World's wifi network but not to either of our home networks. Does anyone have any ideas? Thanks.