I am trying to test ipv6 in my network. my PC (Windows 7)can get ipv6 prefix from the route but can not get ipv6 dns via RA.
I did try to set M and O flag but it is still not work. Below is the ICMPv6 RA package capture. How to fix this problem?

There's no support for getting DNS servers from RA in Windows yet, Windows 7 included.

You can set DNS manually, use dual-stack and IPv4 DNS servers or run separate DHCPv6 server for giving DNS servers to clients.

Does Mikrotik have DHCPv6 feature?

Does Mikrotik have DHCPv6 feature?

currently no, but it will be soon introduced.