What does "Use IPv4 connectivity" do when using IPv6 via PPPoE

[NKnusperer]

As the subject implies, what exactly does the "Use IPv4 connectivity" checkbox do when establishing a IPv6 connection via PPPoE and when it is required?
Is this something dictated by the ISP or the modem configuration?
My ISP provides a dual-stack solution and I've to check this in order to get IPv6 working, however I've also seen people on the internet that does not.

Thanks

[franco]

It depends on the ISP. If IPv6 is supplied over the PPPoE connection you need to check that setting, if it is delivered in parallel to PPPoE leave unchecked.


Cheers,
Franco