In order to disable IPv6 on newer OS X versions, you will need to run a command through the Terminal application. Please note that any changes to the network preferences may revert this setting and the command may need to be run again.
1. Open Finder
2. Click on Applications
3. Click on Utilities Folder
4. Double Click on the Terminal app
5. Run the following command in the terminal window:
sudo networksetup -listallnetworkservices
This will list all of your network interfaces and their names.
6. Identify the network interface you are using, most commonly Ethernet or Wi-Fi. Use the following command in the terminal window to disable IPv6 on that interface. Please note that you may have to use quote marks to envelope the interface name. A few examples:
sudo networksetup -setv6off Ethernet
sudo networksetup -setv6off Wi-Fi
You will be prompted to enter your OS X administrator password. Afterwards, IPv6 will be disabled.
While usually not necessary, if you wish to re-enable IPv6 on your device, you can simply run this command in the terminal:
sudo networksetup -setv6automatic Wi-Fi
sudo networksetup -setv6automatic Ethernet