|How is the laptop connected to the router (cable or WLAN)?|
Have you checked the whole connection, starting from the wall plug (internet) to the computer.
Wall Plug (internet) -> Splitter -> Router (WAN)
Router (LAN) -> PC (LAN)
Are you able to go into the Routers configuration page from the wired PC, when the internet connection is lost?
Please send a reply, if you solved the problem !!!