Could a cantenna be hook up to a wi-fi router for multiple laptops?
“Could a cantenna be hook up to a wi-fi router” — Yes, if the router has an external antenna connector for you to connect the cantenna to. “for multiple laptops” — Only if they’re all in the same direction from the router. Remember, a cantenna is highly directional; that’s how it gets better signal strength (by focusing on a relatively narrow cone rather than broadcasting/receiving in all directions). If the cantenna isn’t pointed at the other machine, you will get worse signal strength, not better.