@RedeviL Android does not support DHCPv6. Use SLAAC + RDNSS.

  @RedeviL 

I fully agree with @Divad : try to use SLAAC + RDNS or MDNS or whatever you want to use to get a DNS.

DHCPv6 has two flags to indicate its capabilities on network : M as managed (what you are trying to do) and O as other configuration (used to tranfert IPs of local DNS, NTP, SYSLOG, SIP, etc server's IP for application layers).

DHCPv6 in managed mode is mostly for corporate use where the administrator needs to control all devices on the network including your own, up to initiate no-trust protocols to validate each device over time.

However the finest use of DHCPv6 is for router configuration through DVHPv6-PD (prefix delegation). Using DHCPv6 on client devices for SOHO stuff is a self inflicted pain. thus the exception appears if you want to be autonomous on your own network. Your router does the DHCPv6-PD client to get IPv6 network addresses to manage from upside router, and then it manages all your devices by selling IP to each of your devices through SLAAC including changing ones for your own security. At home i change my active IP every hour for example on devices communicating on the external network. The fixed IP is kept in backup and mostly used for accessing my own local servers. And theses servers never use the same IP to go "outside".

Keep in mind that you can have any address number you want on an interface, it will be usefull to you ! On the laptop i'm using here, i ve got at least 5 on the wifi interface:

• one local link begining by fe80::...
• one root external IP i won't publish which is not used except if i need my laptop to be joined.
• one dynamic secure IP i won't publish here. it is used to get external link at this very moment.
• one obsolete and expiring one i won't pulish. it is used to continue and finish the comm established some time ago
• another obsolete and expiring one... but older ! still expiring.
• one local address in FD::/8 which is used to communicate on my own network but is never routed outside. this is the norm for that range. it is mostly used when the router fails and thus when all dynamic IPs are removed. My network is then still robust in case of outage ! As i'm using some IoT it is important to me.

Everything here is managed by SLAAC + RDNS + MDNS + DHCPv6-DNS : all devices feed on what they need or can afford. Only my router feels the pain of dealing with IP from DHCPv6. SLAAC is the way to go in my case : it is simplier to manage as most of it does not need my intervention. the router get one IP from the upstream router, then gets a subnet and affects it to one interface. on which a slaac server is running and distributing automaticaly the dispatched addresses range. it is also configured to distribute my own fd::/8 from its configuration setup to my whole personnal lan.

Some ISPs allow you to get several external IP ranges... you'll be able to configure one network for unsafe IoT, one network for guest, one network for familly, one for your job,etc if your ISP plays as per the rules.  For this you'll need DHCPv6-PD. My own ISP allows me to get 254 different networks i can manage myself in theory but they've secure the customer router by recording its MAC vs the delegation... So practicaly only one is usable. But i can do what i want in my home with my own router before getting to the one of the ISP. Even in this configuration, DHCP in managed mode is a kind of hell.

So go SLAAC !

Regards,

Eric.