First off, I'd connect directly to the modem with a wired connection and see if it still happens. If not, it's probably the router that's the issue. If it still happens, it's either the modem, ISP, or your computer. Also, try connecting the laptop using a wired connection and see if it experiences the same issues with the router. If so, that would seem to indicate it's not your computer.
Narrowing down the possibilities is what we need to do first.
Narrowing down the possibilities is what we need to do first.