Need help fixing my NAT for Xbox 360 w Airport Extreme 5th gen

Okay, so the problem you're having is likely due to your Airport Extreme ignoring stuff (as a security measure) that Xbox Live is sending the Xbox. While there are a few ways to deal with this, I've generally found the easiest is to ensure your Xbox is given the same IP address by the AE every time it connects, and to set the AE to then not block anything sent to that IP address.

First we need to get the Xbox's wireless MAC address, which you can find on your Xbox by going to Settings, System Settings, Network Settings, selecting your wireless network from the ones that appear, Configure Network, Additional Settings (push the left thumbstick to the right), and finally Advanced Settings, then the MAC address should be displayed.

Just to be clear, a MAC address has nothing to do with Apple's computers. It actually stands for Media Access Control and is a quasi-unique code that nearly every network adapter has. We're using it here so your Airport Extreme can easily recognise the Xbox.

Now you've got the MAC address for the Xbox, open AirPort Utility, select your Airport Extreme and click Edit, then the Network tab. Click the plus button under the DHCP Reservations box, type Xbox 360 (or whatever you want) as the description, type the Xbox's MAC address into the MAC Address box, then click the IPv4 box, change the last number after the . from 2 to 35, and click Save.

Now we have the Xbox getting the same IP from the AE every time, we need to tell to stop filtering stuff that's sent to that IP.

On the same Network tab in Airport Utility as before, click the Network Options button, tick "Enable default host at:" and enter 35 as the last two digits (so it matches up with the full IP address in the IPv4 box earlier). Finally, click Update, and when your Airport Extreme has finished restarting, try the connection test on the Xbox again and (hopefully) bask in the glow of a nice open NAT setting.

Okay, so to clarify:

1. What have you got selected as the Router Mode on the Network tab, and did you just change it?
   
2. What cable modem do you have?

If you open Airport Utility, click your Airport Extreme, edit, then select the Network tab, what does it say next to Router Mode, and did you end up changing it in the process? Also, is it saying anything about a double NAT by any chance?

Just realised you're using the old version of Airport Utility, which explains the lack of a Network tab, though "Share a public IP address" tells me what it's doing. On the same Internet Connection tab (under Internet), what does it say next to "Connect Using"?

Okay, so I'm pretty sure what's happening at the moment is that your modem is trying to act a bit like a router and is therefore doing NAT and DHCP, which the Airport Extreme is also trying to do, so they're conflicting with one another a bit.

Fortunately a bit of Googling indicates that your modem can be put into what's known as Bridge Mode, where it just handles the first bit of talking to your ISP, letting the Airport Extreme authenticate you as a customer and then actually act as the router entirely.

Before you start you'll need to make sure you've got the username and password for your ISP, the one that the modem itself uses to connect. Have you got those?

They should be able to, though you can probably get at least the username by logging into the modem itself and having a look around. Will likely be http://10.0.0.1.

Be aware that until you've done the second step, which requires your username and password, you won't be able to connect to the internet etc, and in enabling Bridge Mode as it warns in the last step, you'll lose easy access to configuring the modem without manually setting your IP to get to the admin screen.

Once you've got your username & password, you'll need to firstly follow the instructions here to switch the modem into Bridge Mode, though once you're logged into the modem I'd recommend heading over to Maintenance, Tools, Configuration, then click the Backup button to save a copy of all the current settings your modem has before you change anything. That way if it all goes pear shaped, you should be able to use the reset button on the router to reset everything back to defaul settings, then restore stuff from your backed up configuration file.

http://qwest.centurylink.com/internethelp/modem-zyxel-660r-bridged.html

Then, to actually get back online, open Airport Utility, select your Airport Extreme, click Internet, then on the Internet Connection tab, click the dropdown next to Connect Using and change it from Ethernet to PPPoE, enter your username and password, ensure Connection is set to Always On and Disconnect if Idle is set to Never, then click update.

Once the Airport Extreme has restarted it should connect to your ISP and your connection should be back, hopefully, finally, minus any Xbox Live or other issues 🙂.

I'm pretty sure the question it's asking is related to the modem currently trying to do DHCP/NAT as well, so should be something that gets solved via Bridge Mode.

Welcome to the club :)

My xbox(Ethernet) to AirPort Extreme is either open or moderate. I have resorted back to the automatic configuration on the Xbox with nothing special on the router. I would take every setup angle and sometimes it still resorts back to moderate. I chalk it up as no upnp on the apple router. Strict is bad, so I would try these steps.......my modem is in bridge mode, so I would 100% follow up with that like hopkapi said.

You can save the MAC address like hopkapi said or just take the next step. When you go into advanced tab, hit dhcp and nat, and plug in a default host. Make sure it's in the range...do 10.0.1.10.

This will place that IP address in the DMZ and allow all ports needed basically. If its a port issue instead of a modem causing a double nat, you will know from doing this.

Go to your Xbox and select Ethernet, configure, manual.

Ip: 10.0.1.10

Sub: 255.255.255.0

Gateway: 10.0.1.1

If your still pulling stick, most likely your modem will have to be in bridge mode. Talk to your ISP like hopkapi said.