IPv6 /56 block?

[BeachGuy]

I searched but didn't find the answer. I have Merlin v3006.102.6. Spectrum ISP. I am trying to setup IPv6 correctly. Asus doc says "WAN Connection Type is set to [Automatic IP], please select [Passthrough] for the IPv6 Connection Type https://www.asus.com/us/support/faq/113990/
That doesn't work, only works if I set to "Native" then I get full IPv6 connectivity. However I've read that WAN Prefix Length /56 addresses is better than /64. When I put 56 (or 0) in the WAN Prefix Length field and apply it always comes back with LAN Prefix Length 64. I tried both the following with unplugging modem/router for 15 minutes to reset, starting modem first and letting it fully connect but still get /64 addresses.
nvram set ipv6_duid="DUID-EN"
nvram commit
Setting MAC address to different one

Is this an ISP limitation, ASUS firmware or am I configuring something wrong? Maybe WAN Prefix Length is 56 internally but LAN Prefix Length is always 64? Do I need to call ISP (Spectrum) and ask for /56 block?

 

[Ripshod]

When using the native setting in IPv6 everything is automatic from your isp. Yes, your isp is giving you a /64 block because that is what they support. I don't see you getting very far asking for a /56.

 

[BeachGuy]

When using the native setting in IPv6 everything is automatic from your isp. Yes, your isp is giving you a /64 block because that is what they support. I don't see you getting very far asking for a /56.

Ok thanks. Everything's fine and I probably don't need /56 just trying to figure out how all of this works in router and ISP (smaller number = bigger blocks?).

 

[Ripshod]

smaller number = bigger blocks?

 

[dave14305]

Maybe WAN Prefix Length is 56 internally but LAN Prefix Length is always 64?

This is likely the case. Look in the file /tmp/wan0_bound6.env to see what the ISP is sending. The firmware only assigns a /64 to the LAN and doesn’t know what to do with the extra subnets.

You should also see a system log from “dhcp6 client” stating what was requested and received.

 

[BeachGuy]

This is likely the case. Look in the file /tmp/wan0_bound6.env to see what the ISP is sending. The firmware only assigns a /64 to the LAN and doesn’t know what to do with the extra subnets.

You should also see a system log from “dhcp6 client” stating what was requested and received.

cat /tmp/wan0_bound6.env
PREFIXES=XXXXX::/64,604800,604800,class=00093168
ADDRESSES=XXXXXXXXX/128,604800,604800

"You should also see a system log from “dhcp6 client” stating what was requested and received.". How do I view this, what file?