I think there is a bug in airport firmware 7.6 with how spanning tree works in addition to problems with the Uverse router. Having an Airport with a uverse 2wire 3801 and gigabit switch will not work. Putting the extreme in NAT mode with DMZ plus behind the uverse resolved the problem.
Uverse 2wire 3801 router
3801 provides prioritization for upstream traffic so skype and VoIP work better when doing a lot of stuff on Internet
Airport extreme firmware 7.6
two airport express 802.11n hardwired to extreme. Set up in bridge mode. All access points have same SSID "create a network" to enable roaming. Ignore anything to do with extending a network. firmware 7.6
two gigabit switches
Netgear GS608 - 8 port gigabit switch
Trendnet TEG-S80g - 8 port gigabit switch
100BT 5 port switch - did not figure into problem
Three Uverse set top boxes wired on Ethernet. They have to be wire directly to the 2wire box to work correctly. See: http://forums.att.com/t5/Features-and-How-To/At-amp-t-U-Verse-modem-setup-Airpor t-Extreme/td-p/2300785
However, you need to be careful to place your own PCs and other internet devices on the network created by your gear (airport extreme in your case), but keep AT&T's set top boxes for the IPTV services IN FRONT of your own router - so they remain on AT&T's provided network.
So it would work like this ...
Network 1: 2wire RG (4 lan ports) -> Any Set tops, and to the WAN port on your AirportExtreme
Network 2: Airport Extreme LAN ports -> to any computers or internet devices (but not AT&T set top boxes).
The RG prioritizes the traffic for your Uverse Voice and your Uverse TV ahead of internet data traffic, as it rationalizes data heading out of your home. If you place your own equipment in that equation (like putting AT&T set top boxes behind your Airport Extreme) the performance and function of your AT&T set top boxes could really flake out on you.
Everything would be working fine, then intermittently all my wifi access points would stop working. ~6,000 ms latency, dropped packets. Ethernet worked fine. Here is an example of my macbook pinging the extreme when associated with the extreme over wifi with a strong signal.
ping: sendto: Host is down
Request timeout for icmp_seq 23
Request timeout for icmp_seq 24
64 bytes from 192.168.1.64: icmp_seq=25 ttl=255 time=267.051 ms
Request timeout for icmp_seq 26
Request timeout for icmp_seq 27
Request timeout for icmp_seq 28
64 bytes from 192.168.1.64: icmp_seq=26 ttl=255 time=3402.599 ms
Request timeout for icmp_seq 30
Request timeout for icmp_seq 31
Request timeout for icmp_seq 32
64 bytes from 192.168.1.64: icmp_seq=30 ttl=255 time=3060.673 ms
64 bytes from 192.168.1.64: icmp_seq=34 ttl=255 time=24.115 ms
64 bytes from 192.168.1.64: icmp_seq=35 ttl=255 time=31.056 ms
64 bytes from 192.168.1.64: icmp_seq=36 ttl=255 time=39.828 ms
It looks like the 2wire 2801 router has a problem with spanning tree when interoperating with gigabit switches and airports. There is interplay with the airport.
I did not have this problem until the 7.6 airport firmware. I had been using the Netgear hub for about a year with the extreme in bridge mode. I added the Trendnet hub and upgraded airport firmware at the same time which made fault isolation difficult.
Set up airport expresses hard wired to extreme
Connect gigabit switch anywhere to network
Dettach one computer from wifi then reattach, then all wifi stops working. It takes a few seconds for the problem to propagate.
Ethernet still works fine
Connect to 2wire with ethernet
Set 2wire route to have subnet as 192.168.2.x
Set extreme in NAT mode behind 2wire. It will complain about double NAT. Override the warning. Set the subnet to 192.168.1.x so you don't have to change any static IP addresses. Note that 2wire uses 192.168.1.254 as default route whereas airport uses 192.168.1.1.
I set DHCP to start at .10 to leave the lower addresses for assigning static IP addresses to computers I want to expose outside the firewall.
Go into firewall settings. Select airport extreme. Select the bottom setting which is "DMZ Plus". When you go into the airport extreme settings, you will now see that it has the uverse public IP address on its WAN port. NAT port mappings work fine on the extreme behind the 2wire router.