Setting Link Local address as preferred IPv6 DNS server

[bojangofet]

Hello,

I have a DNS server on my home network that I'd like to set as the preferred DNS server for both IPv4 and IPv6. I have a CAX80 router/modem combo. 

For IPv4, I was able to set it up no problem under the "Internet Setup" settings. 

For IPv6, I need to use my DNS server's link local address in order for it to operate privately. If I try that, I get the error below (requiring that I use a global address).  

The only related post I could find is this one, where the guy doesn't actually find a solution but instead finds a 3rd party firmware to allow it. It seems other brands (Asus) seem to allow this natively, not sure if it's a Netgear thing? 

I prefer not to have to set IPv6 for all the devices on my network if that can be avoided. Any help that doesn't require changing the native firmware would be appreciated! 

[plemans]

You are getting the wrong ipv6 info. 

Reason I say that is in your post, I can see above that your LAN delegated prefex preference is to start at the 2601:..........

so if you have a device on the network with an ipv6 address, it'd start with that. 

Problem is on private networks, the FE80 is basically saying its locally administered link-local address. (pita)

It needs to be the global address that starts with the 2601. 

Try setting up the ipv4 and ipv6 address to use your isp's.

Then after the router reboots, disable/reconnect your network connection. 

then go to the ipconfig through the command prompt. When you do that, it should give you your ipv6 address and not just the local link one.

Thats what I had to do with my pihole to get the ipv6 address.  

[bojangofet]

Hello, thank you for the reply!

I do have a global unicast address I can use, but I prefer not to use it. My ISP could cause the DNS server's GUA to change, which makes it a less preferable choice as a permanent router setting. 

It may not be possible for this brand/model to allow a non-GUA as the preferred IPv6 address, which is fine. I just wanted to know so I could try and find other routes to solve the problem. 

[plemans]

If you're using it for pihole, why would you be concerned? 

In terms of the ipv6, certain parts of it are for the global and others for local. 

And if the pihole is set with the specific ipv6 address for that computer, it shouldn't be changing. I've been using it for over a year without issues. 

[bojangofet]

The IPv6 GUA network prefix (the one you pointed out in your original reply) is not static and is in part delegated by Comcast (my ISP). But to your point, just because they can change it doesn't mean they will. It will depend on your location, your ISP and I think your modem how frequently it changes. I would see using the GUA as a temporary solution. 

You can point devices on your network to a DNS server using any of the server's IPv6 addresses (e.g. Global, Unique Local, or Link Local) so why not choose one that is not influenced by your ISP? Choosing a fe80::/ or fd00::/ address is the preferred route for those that have a router willing to accept a non-GUA address, and is the reason I'm asking here how to make my Netgear router do the same.

[plemans]

You can either use the full ipv6 address for your device or disable ipv6 and just use ipv4. 

sure they're subsets of it, but for it to be the dns server, you need the global one on netgear. 

I've been using it for years and its worked fine. I usually have the same ipv6 address for the computer. it'll change whenever I swap modems but thats easy enough to go in and change