@TwoEyedJack 

This option binds the WAN IP address on the status page in router's web management interface to the DDNS record.

If the AX20 WAN IP address is a private IP address (whether dynamic or static), it's not recommended to turn this option ON.

Private IP addresses are in these ranges:

• Range from 10.0.0.0 to 10.255.255.255 — a 10.0.0.0 network with a 255.0.0.0 or /8 (an 8-bit) mask
• Range from 172.16.0.0 to 172.31.255.255 — a 172.16.0.0 network with a 255.240.0.0 or /12
• A 192.168.0.0 to 192.168.255.255 range, which is a 192.168.0.0 network masked by 255.255.0.0 or /16
• A special range 100.64.0.0 to 100.127.255.255 with a 255.192.0.0 or /10 network mask; this subnet is recommended according to rfc6598 for use as an address pool for CGN (Carrier-Grade NAT)