Port-Forwarding on the Arris NVG589 Gateway

@Richroc, it is not possible to configure port forwarding of the same port(s) to multiple devices behind any NATting router.  Cannot be done.

There are two ways to get multiple XBOXen behind the Gateway to work:

1) Pay the monthly fee for a block of public static IP addresses and assign one to each XBOX.

2) Purchase a Router that has UPnP capability and install this router between the gateway and your XBOXen, and configure your gateway to put this router in its DMZplus/IP Passthrough zone.  This works because the software in the XBOX will negotiate via UPnP to use non-standard ports for the additional XBOXen. 

Most consumer routers will do.  Most have Wireless as well, and theirs is probably better than the Wireless signal provided by the U-verse Gateway.  I'm partial to the ASUS line myself, though Netgear makes fine gear too.  I've had good success with D-link, and others will recommend Linksys.

Richroc - your R700 is probably set as AP or some other mode, make sure you have it set to "router mode", this is under advanced->advanced setup->router / ap / bridge etc...

if you do though you will probably have to follow this guide to properly configure passthrough on the att modem and fully leverage all the functions of your router:

http://www.dslreports.com/faq/17734

Thanks...I followed the instructions on my NVG599 and can now play two Xbox destiny characters on the same fire team. You saved me buying another modem, plus a basket of technical headaches setting that up. Your help is greatly appreciated.

The follow up note not to worry abou the warning that the Uverse tv service might not work was important...I almost chickened out.