Server, software update system, distribution method, and non-transitory storage medium

A non-transitory storage medium storing a distribution program in order to distribute update data for software for an electronic control unit mounted on a vehicle that is executable by a computer including a processor, the non-transitory storage medium stores priority information indicating respective priorities of a communication module and a smartphone, the communication module being mounted in the vehicle, and the smartphone being configured to communicate with the vehicle, the distribution program causing the processor to execute the following steps:

• determining, based on the priority information, whether the communication module has a higher priority than the smartphone or whether the smartphone has the higher priority than the communication module;
• transmitting, based on receipt of a request from the vehicle, the update data to the communication module when determining that the communication module has the higher priority than the smartphone;
• and
• transmitting, based on receipt of a request from the smartphone, the update data to the smartphone when determining that the smartphone has the higher priority than the communication module to allow the update data to be transferred from the smartphone to the vehicle, wherein:
• when communication with the communication module is disrupted, transmitting the update data to the smartphone even when the communication module is mounted on the vehicle such that the update data is provided to the vehicle via the smartphone even when a server cannot communicate with the vehicle in order to perform a software update at an appropriate time.