My Macbook Pro running Mavericks picks up my ISP's (native) IPv6 support with automatic configuration just fine on bootup. I'm using an AirPort Extreme 802.11ac (2013) with default settings.
If then connect to an IPv4-only VPN, I lose IPv6 connectivity, as expected.
However, when I disconnect from the VPN, my Macbook Pro will not pick up IPv6 from my ISP until I reboot, as not expected. Configuration remains on Automatic, it just won't configure itself.
How can I make it immediately reconnect to IPv6 when I quit the VPN?