Please ask your Internet Service Provider or google/bing or look at the technical specification of the (broadband-access-)interface for the network of your ISP.
Further Note: We have no MultiWAN IPv6 support. Only the first WAN interface can/will have IPv6 right now.
This is the default state, IPv6 disabled by default. (IPv6 traffic will still flow/work if in access point mode for example.)
This setup is probably one of the most used. It provides native IPv6 connectivity for your network including the possibility to assign different IPv6 address ranges for bridge 0 (br0) to 3 (br3) if you get an prefix with length smaller than 64 (for example 60 or 56) from your internet service provider. The option to assign IPv6 address ranges for bridge 1 (br1) to 3 (br3) is only visible if the bridges do exist, see basic network setup.
Example setup for German Telekom ISP:
Europe biggest telecommunication company provides/supports a dual-stack setup (IPv4 & IPv6) using an ADSL1/ADSL2(+)/VDSL or fiber connection. Note: German Telekom provides a prefix length of 56 for private customer (by default). 64 (default config for Tomato) will also work.
Extended options for IPv6 DHCPv6 PD - if bridges 1 (br1) to 3 (br3) do exist:
ttbd. or ask google or at https://www.linksysinfo.org/index.php?forums/tomato-firmware.33/ :)
The network prefix contains the most significant bits of the address. The leading bits of the addresses are identical for all hosts in your assigned network.
Default Prefix Length: 64 (bits) (can be changed to 56 bits for example)
Check for ISP's that require only a Prefix Delegation (usually PPPoE (xDSL, Fiber) connections)
IPv6 RA (via WAN ⇒ IPv6 ICMP) will take care of adding the default route, so that this option should not be enabled/required! BUT: some ISP's, Snap (NZ), Internode (AU) may need the default route / workaround –> Tomato user can decide
Tomato user can add or specify DNS addresses. (Note/Example: If you are using DHCPv6 with PD for example with German Telekom ISP you will get two IPv6 DNS addresses automatically - but you are still able to specify static DNS addresses if needed/wanted)
Note: Using DHCPv6 with Prefix Delegation this option will always be enabled for WAN. The user can not disable it!