Iptables for openvpn access server config
Everything will work just fine-but none of your IPv6 traffic will be encrypted. The bad thing is that you won't notice the difference. The result is that whenever you connect to a server that has an IPv6 DNS entry, your traffic will probably not be routed via IPv4 and therefore not go through your OpenVPN connection. Hence, your laptop will automatically receive an IPv6 address. What you don't know is that the coffee shop uses a service provider that supports IPv6. Let's say you are in a coffee shop with your laptop, and as usual, you connect via VPN because you are in an insecure network environment. I think many OpenVPN users are unaware of the consequences of an IPv4-only configuration on the Internet, with fast-growing support for IPv6.
The main reason you want your OpenVPN setup to support IPv6 is, again, security. Every server on the Internet can still be reached with IPv4 thus, beefing up your OpenVPN setting with IPv6 seems to violate Einstein's principle. The other question you might ask is why you need IPv6 for OpenVPN. Thus, I decided to write my own guide, which honors Albert Einstein's principle: "Everything should be made as simple as possible, but not simpler." Perhaps even worse are those posts that only explain the IPv6-related settings but fail to mention the other minimum requirements to get OpenVPN going.