A printer includes a printer-side memory that stores first connection setting information for establishing a communication connection with one or a plurality of terminal devices, and in accordance with second connection setting information for establishing a communication connection with an access point received from the terminal device with which a communication connection has been established, a printer-side processor that establishes a communication connection with the access point, wherein when the printer-side processor determines the terminal device having a communication connection to be the terminal device connected by mistake, disconnects the communication connection with the terminal device, and changes the first connection setting information stored in the printer-side memory.