After update from Windows 10 to Windows 11 - IPv6 RFC 6106 / RDNSS (Router Advertisement Options for DNS) stopped working

Question

I was using Windows 10 Education (most recent build) with automatic configuration of networking on Ethernet interface. Both IPv4 and IPv6 configuration was obtained from network correctly (with no problem for many years.) IPv4 address and other parameters were obtained via DHCP, IPv6 parameters via ICMPv6 NDP (parameters taken from Router Advertisement message from router). It was working, including RFC 6106 support (RDNSS (Router Advertisement Options for DNS)), added to Windows 10 several years ago. IPv6 DNS servers were preferred by OS all the time.
Today, I updated my OS to Windows 11 Education. I have 21H2 version, build 22000.708 with available updates. Whole update was successful, with 0 error messages.
No configuration of networking was changed.
However, IPv6 recursive DNS server addresses obtained from Router Advertisement (RA) message (RFC 6106) are ignored by Windows 11. OS has only IPv4 DNS configuration available. RA message is obtained (I have checked it in Wireshark), both temporary and stable IPv6 address are configured with help of SLAAC, however, option #25 including DNS server addresses is ignored by OS or configuration of IPv6 DNS is not successful.
I have already tried, with no change:

• restarting OS,
• resetting networking of whole OS,
• ipconfig /release6 and ipconfig /renew6,
• netsh interface ipv6 set interface ethernet rabaseddnsconfig=disabled and, then, netsh interface ipv6 set interface ethernet rabaseddnsconfig=enabled,
• checked the configuration of DNS - there is no manual configuration inserted, there is no configuration of DoH,
• googling possible solutions or workaround relevant for Windows 11.

Based on comparison available from https://en.wikipedia.org/wiki/Comparison_of_IPv6_support_in_operating_systems , RDNSS support was added to Windows in Creators Update, but there is no information about Windows 11 so far. Is this RFC 6106 support part of Windows 11?

In my case, there is dual-stack network. Missing IPv6 DNS configuration is not so significant issue. However, in case of IPv6-only network (for instance with DNS64 and NAT64 services), it will totally block DNS communication.

Answer 1

MS - do something about it ... after all, in the 21st century we won't be manually setting up ipv6 DNS servers. It works on all other systems only W11 doesn't.

Answer 2

If was testing this configuration last week. I noticed the following:

• If IPv4 and IPv6 are enabled with default settings (with DHCP) only DNS servers are configured which are provided by the DHCP server for IPv4 and IPv6. If no DHCP servers is configured for IPv6 and only Router Advertisement RDNSS is configured, the IPv6 DNS server are not configured (as you stated).

However,

• If you disable the IPv4 protocol on your nic, and only leave the IPv6 protocol enabled, you will notice that the NIC will configure the DNS servers via RDNSS.

So it does seem to work if you use IPv6 in a single stack setup.

Answer 3

I have this problem also
Windows 11 IGNORES my Routers RA IPv6 DNS config.
My iPhone and Macbook work fine.