Hi,
I think there is a little typo bug in 0001-base-files-Better-IPv6-defaults.patch patch to /bin/config_generate
Line 179 call set network.$1.ip6ifaceif='eui64' but netifd only support option ip6ifaceid not ip6ifaceif .
My IPv6 config is still working OK with option ip6ifaceif 'eui64' in /etc/config/network .
Regards,
Laurent