Dual stack - assigned IPv6 address is not set for ipsec0

Configured Native iOS VPN on MacBook. On turning on, config request for both ipv4 and ipv6 is being sent and the server assigns both IPv4 and IPv6 address. On the MacBook, we observe that ipsec0 is having correct ipv4 address (172.16.1.2) but incorrect ipv6 address (fc00::0a instead of 2001:x:x:x). i.e. ipsec0 is getting link-local IPv6 address instead of assigned address. How do we fix this?