Feature Request: Enhanced IPv6 DNS Configuration

1. User Profile & Objective

• User Profile: A technically proficient home user or "prosumer" managing a local network with custom services. This user values network privacy, security, and performance, and often runs services like a local ad-blocker (e.g., Pi-hole) or a recursive DNS resolver (e.g., unbound) on a dedicated device like a Raspberry Pi.
• Objective: To configure the router to direct all network clients to use a self-hosted DNS server for all IPv6 DNS queries. To ensure stability, the DNS server is identified by a permanent, non-public IPv6 address (a Unique Local Address, or ULA).

2. Use Case Scenario & Current Problem

This use case describes the standard, best-practice steps for setting up a local DNS resolver on an IPv6 network and details how the current router firmware prevents it.

1. Setup Local DNS Server: A DNS server (e.g., unbound) is configured on a local device (e.g., a Raspberry Pi).
2. Assign Stable IP Address: To ensure the DNS server's address never changes, it is assigned a static Unique Local Address (ULA) from the fd00::/8 range (e.g., fd99:2211:966c:efae::10). This is a critical step because the public IPv6 prefix provided by an ISP is dynamic and subject to change.
3. Attempt to Configure Router: The user accesses the router's web interface to set the static ULA of the DNS server as the network's resolver.
4. Encounter Blocker #1 (Invalid Validation): The user navigates to the IPv6 Internet/WAN DNS settings and enters the valid ULA of the local DNS server. The router's firmware rejects this address, claiming it's an "invalid format." A test confirms the firmware will accept a public IPv6 address (2600:...), proving the validation rule is specifically and incorrectly blocking internal-range IPs for the WAN DNS setting.
5. Encounter Blocker #2 (Inflexible LAN Configuration): The user attempts a logical workaround by setting the DNS server on the IPv6 LAN settings page instead. However, the firmware provides no option to manually specify a DNS server for the LAN. The LAN DNS assignment (via RDNSS) is permanently coupled to the WAN DNS setting, offering no path to bypass Blocker #1.

3. Conclusion

The current firmware makes it impossible to use a local DNS resolver with a stable IPv6 address, which is a standard practice for advanced home networking. The combination of flawed WAN IP validation and the inability to configure LAN DNS settings independently creates an inescapable roadblock.

4. Proposed Features

To resolve this, the following features are requested:

1. Allow ULAs in WAN DNS: The validation for the IPv6 Internet/WAN DNS settings should be corrected to accept valid IP addresses from the Unique Local Address (ULA) range (fd00::/8).
2. Provide Independent LAN DNS Fields: A feature should be added to the IPv6 LAN configuration page to allow an administrator to manually specify IPv6 DNS server addresses for the LAN. These addresses would be advertised to clients via RDNSS and/or DHCPv6, independent of the WAN DNS settings.