An information processing system according to the present invention includes: a relay device communicates with a server through a first communication line and a device through a second communication line, and relays data between the first communication line and the second communication line; an auxiliary relay device communicates with the server through a third communication line and the device through the second communication line, and relays data between the third communication line and the second communication line; and a management device detects a failure on the first communication line and controls the auxiliary relay device in such a way as to establish an alternative communication channel by using the third communication line and the auxiliary relay device when the failure is detected and to deliver the auxiliary relay device to a location where the auxiliary relay device is connected to the second communication line.