With the massively increasing amount of IP addresses required by the global network each year, IPv4 can no longer meet the demand. That’s why IPv6 was introduced — to allow more unique TCP/IP identifiers to be created for each user.
While most of the internet uses the IPv4 protocol, there are ISPs that provide support for IPv6 as well. It is our duty to make sure that users are aware that, for the time being, our servers are compatible with the IPv4 internet protocol only. However, ProtonVPN takes active measures to prevent any possible IPv6 leaks.
ProtonVPN applications block all IPv6 traffic by default. To be precise, IPv6 traffic is disabled; any potential IPv6 traffic is routed to a black hole (null route) to ensure your device cannot make connections over IPv6. That way only IPv4 connects are possible to ensure your real IP address is not leaked. Also, by disabling IPv6 traffic on your network, your internet connection performance shouldn’t be affected as most internet services are accessible via IPv4.
You can configure your router to block all IPv6 traffic, however. Different routers feature different settings but most of them have an option to turn off IPv6 completely. This way you wouldn’t have to disable IPv6 on each of your devices, but keep in mind that it is not possible to turn off IPv6 traffic on Android and iOS. In order to disable IPv6 on your router, please check router user manual or consult with an IT specialist.