To disable the IPv6 VPN protocol on Mac via Network settings:

1. Click the Apple icon on the top left of the screen.
2. Select System Settings.
3. Click the Network icon.
4. Make sure you have the network selected that you are using – usually Wi-Fi at home.
5. Click advanced.

6. Select the TCP/IP tab at the top.
7. You’ll see a line that says Configure IPv6. By default, it’s set to Automatically. Set it to Link-local only, which sets the computer to only use IPv6 within your home, not on the internet. Some MacOS versions may even simply allow you to select Off as an option.

8. Click Ok.
9. You should then restart your Mac.