Ipv6 - subnetting when I have a /64 PD

My ISP gives out ipv6 with a prefix delegation of /64. Is it possible to create multiple ipv6 /68 or /69 subnets on my network? If yes, then how?

I have the ipv4 subnets working to my satisfaction. However, only my main LAN subnet is fully working on ipv6 with internally routable addresses (eg. fda6:... ) and externally routable addresses (eg. 2401:... ). The other subnets only get locally routable addresses. I understand that this is likely that the router / odhcpd is fully adhering to specifications and refusing to create subnets of /68.

The ISP seems to be marketing driven rather than technically driven, providing mobile, fiber, and TV services. Therefore I see little chance of getting them to change.

Theoretically, yes - but you still don't want to go there. prefixes smaller than /64 are possible, however only with DHCPv6 or static assignments, while SLAAC does not work with those at all (hello android and other devices), aside from further fun with privacy extensions and many other problems.

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What if we configure Stateful DHCPv6 to hand IP addresses to Android clients? Simply put SLAAC out of the game, and use DHCPv6 for dynamic IP assignment, along with static (manual) IP address on stationary hosts such as servers and CCTV. It sounds pretty much like IPv4, which we are already familiar with.

Android refuses to implement a DHCPv6 client. Android endpoints never make a DHCPv6 request. This is apparently a design decision at the top.

So any IPv6 network expecting to serve Android endpoints requires SLAAC, including advertising a DNS server in the RA. If there is no DNS advertised in the RA, a DNS must be provided on an IPv4 dual stack or Android will refuse to connect.

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From what I know the RA message only provides prefixes and gateway. It has the O flag (known in /etc/config/dhcp as list ra_flags 'other-config') to tell the hosts to find Other configuration (DNS and domain name) in a Stateless DHCPv6 server.

If Android devices never make DHCPv6 request, how can they get DNS? Maybe by some other mean?

Via the route advertisement.

Edit: ps: https://datatracker.ietf.org/doc/html/rfc8106 IPv6 Router Advertisement Options for DNS Configuration. From 2017.

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