How to set up ipv6 for guest wlan?

Installing and Using OpenWrt Network and Wireless Configuration
1

I've successfully setup a guest wlan for ipv4, using the recipes at https://openwrt.org/docs/guide-user/network/wifi/guestwifi/start
However, when I tried to add ipv6 to the wlan, I saw the routes for the public ipv6 addresses taken over by the guest network and some indications that the public ipv6 addresses were not being setup/distributed on the main LAN. I reverted the guest LAN to ipv4 only.
My ISP provides native ipv6
Protocol: DHCPv6 client
Prefix Delegated: 2401:xxxx:c8xx:f3b1::/64
Address: 2401:xxxx:c0xx::2:d51e/128
Gateway: fe80::2a6e:d4ff:fe97:cbdb
DNS 1: 2401:7400:8888:41::38
DNS 2: 2401:7400:8888:42::5

Thanks for your attention.

2

You need a bigger prefix (i.e. a smaller prefix length value between 48 and 60) since (at least) one /64 subnet is required for each LAN. Hopefully your ISP allows that. Try to request it in the WAN settings.

3

A workaround might the NDP / DHCPv6 relay mode if there is no possibility to obtain a larger upstream prefix.

4

Should I do this in the main LAN or just in the Guest / DHCP / ipv6 settings or both?

Thanks for your attention

5

I tested and my provider only gives/permits a /64

Thanks for your attention

6

How to do this? My ISP gives only /64

7

It's not recommended and probably violates some RFC somewhere (but, then again, your ISP's policy is against RFC recommendations by only issuing you a /64), but you can take the "ugly" steps of manually splitting your /64 into two /65s.

I'm not sure it's worth the effort, as my philosophy around "guest" networks is that "You're lucky enough to get on the Internet at all" when it comes to jumping through hoops to implement niceties, like IPv6, for them.

Edit:

One relatively simple option would be to get a 6-in-4 tunnel from a broker, such as Hurricane Electric, and use that for your guest network. There's slight overhead (20 bytes) compared to native IPv6, but it would likely make your configuration a lot easier!

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8

My ISP has their own router equipment (an Arris device) that provides only /64 prefixes but I can request more than one. Perhaps you can do the same? I had to use wide dhcpv6 client (on a router not using openwrt).

EDIT: specifically it has access to a /60 and then hands out up to 16 /64 prefixes

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