You can obtain the address assigned by the carrier and avoid extra NAT, see Can't place RM520 in IP Passthrough (IPPT) mode - #4 by sirozha
See this for IPv6: RM520N-GL IP Passthrough with Network Adatper Mode
You can obtain the address assigned by the carrier and avoid extra NAT, see Can't place RM520 in IP Passthrough (IPPT) mode - #4 by sirozha
See this for IPv6: RM520N-GL IP Passthrough with Network Adatper Mode