A communication system includes a first device configured to transmit first data, a second device, a third device, a fourth device, and a storage device configured to store correspondence information, and when the second device is in the first state, the second device transmits the first data to the address of the third device, and when the second device is in the second state, the second device transmits the first data to the fourth device, the second device notifies the fourth device of the address of the second device, the fourth device receives the first data and notifies the storage device of the address of the second device, the storage device notifies the fourth device of the address of the third device associated with the address of the second device based on the correspondence information, and the fourth device transmits the first data to the address of the third device.