1. A method for changing a mode by a server, the method comprising: receiving, from a master device, first information related to a mode activated in the master device; identifying at least one slave device synchronized with a mode of the master device based on the first information; generating second information related to a mode of the identified at least one slave device based on third information related to a rule applied per mode of the master device and the identified at least one slave device; and transmitting, to the identified at least one slave device, the second information, wherein the second information is used for mode synchronization between the master device and the identified at least one slave device.