IPv6 (IPV6) is a standard that assigns an address (IP address) to each device, which is indispensable for using the Internet, in a 128-bit configuration. Conventional IPv4, which consists of 32 bits, has a maximum of about 4.3 billion addresses, but IPv6 has an astronomical number of about 340 million (1 trillion times 340 trillion and 1 trillion times more). If all terminals in the world migrate to IPv6, the problem of lack of IP addresses will surely be solved.
That IPv6 isn't just for connecting to the internet. The address is long and rarely overlaps with other devices, and a "link local address" is assigned to the device on the same link (within a range that does not exceed the router). Therefore, in a closed environment such as a local area network (LAN), it is possible to communicate without setting an IP address.
In the conventional IP network (IPv4), the "DHCP server" (the function to assign the IP address to the terminal) installed in the router was used when communicating on the LAN. Similarly, when connecting to Wi-Fi, the iPhone receives an address assignment from the DHCP server of the router/Wi-Fi access point. In an IPv6 network, that processing is basically unnecessary.
In the case of iPhone, IPv6 is used for wireless file transfer technology "AirDrop" and audio/video streaming technology "AirPlay". The idea of whether IPv6 is necessary or not is nonsense, as it is already being used at the base level, which is difficult to separate from systems and other functions. In fact, there is no switch to disable IPv6 in the "Settings" app.
