A display device comprising: a display; a communicator configured to perform communication with a server via at least one wireless network; and a processor configured to execute at least one instruction to: while the display device is in a normal mode, perform a first keep-alive operation according to a first communication protocol by transmitting a first packet to the server and receiving a first response packet from the server, characterized in that the processor is further configured to execute at least one instruction to: generate and transmit, to the communicator, a second packet, which is different from the first packet, for performing a second keep-alive operation according to a second communication protocol with the server, based on data included in the received first response packet, and control the display device to enter a suspend mode after transmitting the second packet, wherein the communicator is further configured to: while the display device is in the suspend mode, perform the second keep-alive operation according to the second communication protocol, which is different from the first communication protocol, by transmitting the second packet, which is different from the first packet, to the server at intervals of a first period. a display; a communicator configured to perform communication with a server via at least one wireless network; and a processor configured to execute at least one instruction to: while the display device is in a normal mode, perform a first keep-alive operation according to a first communication protocol by transmitting a first packet to the server and receiving a first response packet from the server, characterized in that the processor is further configured to execute at least one instruction to: generate and transmit, to the communicator, a second packet, which is different from the first packet, for performing a second keep-alive operation according to a second communication protocol with the server, based on data included in the received first response packet, and control the display device to enter a suspend mode after transmitting the second packet, while the display device is in a normal mode, perform a first keep-alive operation according to a first communication protocol by transmitting a first packet to the server and receiving a first response packet from the server, characterized in that the processor is further configured to execute at least one instruction to: generate and transmit, to the communicator, a second packet, which is different from the first packet, for performing a second keep-alive operation according to a second communication protocol with the server, based on data included in the received first response packet, and control the display device to enter a suspend mode after transmitting the second packet, generate and transmit, to the communicator, a second packet, which is different from the first packet, for performing a second keep-alive operation according to a second communication protocol with the server, based on data included in the received first response packet, and control the display device to enter a suspend mode after transmitting the second packet, wherein the communicator is further configured to: while the display device is in the suspend mode, perform the second keep-alive operation according to the second communication protocol, which is different from the first communication protocol, by transmitting the second packet, which is different from the first packet, to the server at intervals of a first period.