IPv6 address only works under IPv6 network environment. However, as the mainstream Internet structure is still under the IPv4 network environment, you need to enable IPv6 Tunnel for full Internet access. If you are not sure how to configure IPv6 or face any connection problems, please contact your Internet Service Provider.
Note: Your external IPv6 address may be automatically updated by the service provider. However, Synology DiskStation will not remove the old IPv6 address immediately.