In a communication system, an information processing apparatus including a first controller and a memory and a mediation apparatus including a second controller can communicate with each other via a firewall. The mediation apparatus can communicate with a device via a local network. Based on an acquired plurality of instruction information, the first controller generates first commands. When a setup is performed by the mediation apparatus, the first controller transmits the generated first commands to the mediation apparatus, and receives a response thereto. Upon receiving the first commands, the second controller generates second commands based on the first commands, and transmits the generated second commands to the device. One of the first controller and the second controller sets a transmission order for the second commands by setting a priority for each second command A second command having higher priority is transmitted prior to another second command having lower priority.