You don’t technically have to disable IPv6 but most VPN providers don’t support it yet, and as such, personal information can become visible to anyone monitoring the network. For this reason, it’s a good idea to disable IPv6, assuming your VPN doesn’t offer IPv6 leak protection. Here’s how to do this in Windows 10:
Go to Control Panel > Network and Internet > Network and Sharing Center
Click on Change adapter settings in the menu on the left
Find your network in the list, right-click it, and select Properties
Now, simply untick the box labeled Internet Protocol version 6 (TCP/IPv6)