1. read about OSI_model and understand that Internet_Protocol has two current versions, v4 and v6.
2. we (and other participants in the Internet) won't simply switch from IPv4 to IPv6 but (try) to run both simultaneously, technically dual stack
3. a couple of IPv6 transition mechanisms exist

Following components of your GNU/Linux distribution (OpenWrt) must be or become or made IPv6 compliant:

1. kernel? (or just the network stack?)
2. network stack
3. wlan stack
4. netfilter
5. programs

Furthermore both protocols have to work simultaneously.

• RFC6052 - IPv6 Addressing of IPv4/IPv6 Translators
• RFC6146 - Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers