Bridge mode - double Nat?

[#1]

I have an XB6.  I have an asus ac86u router.  I have placed the XB6 in bridge mode and am using my asus router for wifi etc.  Problem is the WAN IP assigned to the asus router is NOT the same as the wan IP that is listed in the XB6.  This is causing a double nat issue. 

How do i resolve this?  I've tried a number of things and nothing has changed.  Is bridge mode on the XB6 not a true 'bridge' mode?

[#2]

The IP that your XB6 has in Gateway mode will be different than your Asus router gets in bridged mode.

This is to be expected, but they should be different public IP addresses.  Not causing double-NAT.

Does the IP your Asus router reports start with 10. or 192. ?  Or something else?