So various things could make this fail. Firstly, if you don't provide a specific IP address for php artisan serve, it will by default use 127.0.0.1, which makes its webserver only accessible from your local host. Try setting the --host flag to your local network IP address.
Secondly, there might be a firewall blocking incoming requests to the port that you are running your webserver on. Make sure that there is an allow rule in place.