Router + ip6 checked / DNS ipv4

Following the tutorial, i went to the setting of my network connections - on my computer - and noticed that IPV4 and IPV6 were checked - default - on Windows 8 and wrote comodo dns in the windows for ipv4. Trying for ipv6, it seemed to be accepted but no … it is not … it is or ipv4, or ipv6 …

Following the tutorial
, i went to the setting of my router and checked IPV6. Of course, it was unchecked before. And wrote comodo dns in the windows. Is has been refused : no support for ipv6.

Reading the others posts about ipv6, i learnt that Comodo Dns is not yet ready for.
In fact it is not really important as long as it works well for ipv4 …

I checked on my router IPV6 (for comodo dns) ; my questions are these one :

Must i unchecked now or does it open a better security unknown large way for IPV4 COMODO DNS ; like a connection trick …
Is it dangerous opening the both rules (ipv4 and ipv6) ?
Why both are checked on windows 8 ?
Should not it be better if the choice was only one Ipv4 OR Ipv6 and not AND ?

solved ; thx.