Defining a nixos-container seems to break IPv6 on the host

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1

I’m trying to make use of nixos-containers to get some isolation between services. However, when I add the below to my configuration, the container starts no problem, and nginx runs inside it, but the host no longer gets any IPv6 addresses on its main interface apart from an automatic link-local one.

Any suggestions where I should be looking for the problem? If it makes a difference, the host’s networking is configured with systemd-networkd. Thanks!

{
  containers.aneurin = {
    autoStart = true;
    privateNetwork = true;
    localAddress = "10.52.65.10";
    localAddress6 = "fc00:52:65::10";
    hostAddress = "10.52.65.1";
    hostAddress6 = "fc00:52:65::1";

    config =
    {
        system.stateVersion = "25.05";

        services.nginx.enable = true;
    };
  };
}