Setting up Airport Base Station with Uverse AND Sprint Airave
The definitive steps that worked for me. I would like to spell them out as much as possible, since many forum posts will say "Set this to that" but in no way tell you how to get to a setting screen.


Set Airport to use WPA2 security (not WPA/WPA2)

Airport Utility > Airport > Wireless > Wireless Security > WPA2 Personal
This may not work for everyone, especially if you have older devices

Set Airport to do DHCP and NAT

Airport Utility > Airport > Network > Router Mode > DHCP and NAT

Set Airport to reserve an IP for your AiRave/Airvana

Airport Utility > Airport > Network > "+" under "DHCP Reservations"
Choose a high number

Setup the Uverse Modem/Router

Turn off the wireless network

Settings > LAN > Wireless > Wireless Interface > Disabled

Verify your Apple Airport is the only thing using your Uverse Modem's Router

Settings > LAN > Status
Devices > Clear List
You want to only see one device.

Set Airport in the Uverse DMZ

Settings > LAN > IP Address Allocation

Firewall > Disabled
Address assignment > Public
WAN IP Mapping > Router WAN IP Address


Verify this worked

Settings > Firewall > Applications, Pinholes, DMZ
You should only see your Airport as the  'computer' in step 1.
Since it is selected, you see the radial button pressed for DMZ


Set up the Airvana/Airave

Manually set the IP to reserved

Advanced > LAN
(May not be necessary)

Set to use it's own MAC address

Settings > Status




Ultimately, I resolved the Airport/Uverse DMZ issue by switching the Airport Extreme from WPA/WPA2 to strictly WPA2. Initially, I didn't have much faith in this approach, but I tried it based on ouquinn's comment. This allowed me to set the Airport in the Uverse DMZ, which I had struggled for hours to do.