A slave device accesses an external network through a master device via a short-range wireless communication channel between the master device and the slave device. The slave device receives a notification message from the master device, wherein the notification message includes information about a intermediate network used by the master device to connect to the external network. And the slave device controls network traffic between the slave device and the external network according to a type of the intermediate network. When a master device uses a network of a cellular network type, use of network traffic in an application on a slave device can be restricted, thereby saving traffic.