macOS Sierra: Use IPv6
IPv6 is a version of the Internet Protocol (IP) that provides more IP address space for Internet users. The primary advantage of IPv6 is that it increases the address size from 32 bits (the IPv4 standard) to 128 bits. An IP address size of 128 bits can support a large number of addresses, even with the inefficiency of address assignment. This allows more addresses or nodes than are available under IPv4. IPv6 also provides more ways to set up the address and simpler autoconfiguration.
By default, IPv6 is configured automatically, and the default settings are sufficient for the majority of computers that need to use IPv6. However, if your network administrator or Internet service provider (ISP) tells you to configure IPv6 manually, follow the instructions below.
Choose Apple menu > System Preferences, then click Network.
Select the network service you want to use with IPv6, such as Ethernet or Wi-Fi.
Click Advanced, then click TCP/IP.
Click the Configure IPv6 pop-up menu, choose Manually, then enter the IPv6 address, router address, and prefix length you received from your network administrator or ISP.
Note: Your router address may be referred to as your gateway address by some ISPs.