Standalone IPv6 VPN Solution for Offline Network

I’m looking for advice on setting up a standalone VPN solution for a unique use case. Here are the specifics:

  1. The network is IPv6-only with no internet access.
  2. Some IPv4-only devices need to communicate with each other over the IPv6 network.
  3. The VPN should encapsulate IPv4 traffic inside an IPv6 tunnel.

What I’ve Tried So Far:

  • OpenVPN Access Server: Works well for general VPN needs but does not establish IPv6-only tunnels. It can transport IPv6 through IPv4 tunnels, which doesn’t meet my requirements.
  • Proof of Concept: Used Windows Server 2022 with Ubuntu on Hyper-V, running OpenVPN. It worked partially but isn’t ideal for a standalone setup.

Potential Solutions Considered:

  • WireGuard: Known for its efficiency and IPv6 support. Unsure about configuring it to route IPv4 over IPv6 in this scenario.
  • SoftEther VPN: Supports dual-stack operation but unclear if it can operate without internet access.
  • Tinc VPN: Flexible and supports IPv6, but the configuration for this setup might be complex.

Questions:

  1. Has anyone implemented a similar solution using Raspberry Pi as the VPN server?
  2. Which VPN software do you recommend for transporting IPv4 traffic over an IPv6 tunnel in a fully offline environment?
  3. Are there additional configurations (e.g., NAT64 or routing) that I should consider to make this work?

Any guidance or experiences would be greatly appreciated. Thank you!

Re your “using Raspberry Pi as the VPN server?”

Wild guess: @Olympics1639 might know, or might know whom, here at the Brave Community, might help.