IPv6 computing a global unicast address

An IPv6 interface will compute its global unicast IPv6 address only if the ipv6 address autoconfig command is issued AND there is an active IPv6 router on that subnet. The autoconfig keyword enables autoconfiguration or SLAAC.

Links:

https://networklessons.com/ipv6/cisco-dhcpv6-server-configuration/

https://forum.networklessons.com/t/cisco-dhcpv6-server-configuration/1116/66?u=lagapides