1. Is it an old dongle? Because Vista is pretty far out of date (and was never a good operating system) (of course, I'm an XP fan. Drivers might be an issue.
2. If the dongle works, is it compatible with the router? Do they speak a common language? ac (newest), b, c, n, g etc?
3. Do they even sell laptops without built in wifi? Why is he using a dongle? Is the wifi router trying to talk to the laptop instead of the dongle? Is the laptop trying to talk to the internal device instead of the dongle?