Apple airport extreme not doing network DNS correctly
Jan 28, 2016 Creating two independent networks with AirPort Express and Mar 19, 2018 Is Double Nat Safer - Ars Technica OpenForum
The Extreme just set up automatically to "DHCP and NAT" - when connected to the SH2 in modem mode. Never had a moments problem with it - no "double NAT" messages, no flashing green or yellow lights - steady green all the way (on it and the Expresses).
airport extreme flashing light error: double nat? | Mac Nov 22, 2007
Open up your Xbox One’s NAT via AirPort Utility – Six Colors
AirPort Utility will also warn you about the double NAT. A third option is to install remote screen-sharing software on another Mac on your network, assuming you have a Mac that you can leave running. Should my Extreme be in bridge mode or DHCP? : applehelp In DHCP mode, the Extreme becomes a router. In bridge mode, it passes the routing onto a difference device. (It is actually more complicated then that, but that is the basic idea.) If you already have a router on your home network, you should set it to bridged to avoid double NATs. If you don't have a router, it should be set to DHCP. network - Configuring AirPort Extreme with Existing Router