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 an intermediate network used by the master device to connect to the external network. The slave device controls its network traffic to 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.