In this case the issue impacted IPV6 native style connection,, No this is not because you didnt get information from ISP, on "native" style connection the router collects this information from Modem via IMCPv6 query and is collecting this information...
it turns out in Version 3.0.0.4.384.5977 update, for what ever reason, asus did some updates to the ipv6 platform, which directly impacted how the router chose to advertise the eth0 style ipv6 connection. it was a change on one line of code that dire...