A local network apparatus which connects an internal network and facilitates a user device to connect to an external network, comprising: a memory configured to store a default account with corresponding default password, the default account facilitating connection to the local network apparatus by a device; and a processor configured to: create a first account based on a request for creating a new account from a first user device (200a-1), associate first authentication information with the first account and store the first authentication information in association with the first account in the memory, the first authentication information being information received from the first user device (200a-1) for authentication with a first service provider server on the external network, allow a second user device (200a-2) to connect to the local network apparatus using the first account instead of the default account, and allow the second user device (200a-2) to access the first authentication information associated with the first account in the memory, and transmit the first authentication information to the second user device (200a-2) whereupon the second user device (200a-2) performs authentication with the first service provider server based on the first authentication information, receive an authentication information for authentication with the first service provider server from the first user device (200a-1) connected to the network apparatus using the first account, and compare a validity date of the authentication information with a validity date of the stored first authentication information, and update the first authentication information with the authentication information when a validity date of the authentication information is longer than a validity date of the first authentication information, and store the updated first authentication information in the memory. a memory configured to store a default account with corresponding default password, the default account facilitating connection to the local network apparatus by a device; and a processor configured to: create a first account based on a request for creating a new account from a first user device (200a-1), associate first authentication information with the first account and store the first authentication information in association with the first account in the memory, the first authentication information being information received from the first user device (200a-1) for authentication with a first service provider server on the external network, allow a second user device (200a-2) to connect to the local network apparatus using the first account instead of the default account, and allow the second user device (200a-2) to access the first authentication information associated with the first account in the memory, and transmit the first authentication information to the second user device (200a-2) whereupon the second user device (200a-2) performs authentication with the first service provider server based on the first authentication information, receive an authentication information for authentication with the first service provider server from the first user device (200a-1) connected to the network apparatus using the first account, and compare a validity date of the authentication information with a validity date of the stored first authentication information, and update the first authentication information with the authentication information when a validity date of the authentication information is longer than a validity date of the first authentication information, and store the updated first authentication information in the memory. create a first account based on a request for creating a new account from a first user device (200a-1), associate first authentication information with the first account and store the first authentication information in association with the first account in the memory, the first authentication information being information received from the first user device (200a-1) for authentication with a first service provider server on the external network, allow a second user device (200a-2) to connect to the local network apparatus using the first account instead of the default account, and allow the second user device (200a-2) to access the first authentication information associated with the first account in the memory, and transmit the first authentication information to the second user device (200a-2) whereupon the second user device (200a-2) performs authentication with the first service provider server based on the first authentication information, receive an authentication information for authentication with the first service provider server from the first user device (200a-1) connected to the network apparatus using the first account, and compare a validity date of the authentication information with a validity date of the stored first authentication information, and update the first authentication information with the authentication information when a validity date of the authentication information is longer than a validity date of the first authentication information, and store the updated first authentication information in the memory.