@cryptoz 

Hello,

As far as I know, the IPv6 address with the fe80 prefix can only communicate in the local network, and it won't communicate over the LAN, which means if you get the fe80 prefix address for the IPv6 connection, you won't be able to access the internet.

The address with the 2001 prefix is the one that communicates over the internet, but don't worry as there is an IPv6 firewall on the router which blocks the external access to the LAN device automatically to protect your internal network and ensure its security, and that firewall currently cannot be disabled.

Hopefully, that answers your question but let us know if you need more details.