Airport, DSL and IP problems! Oh My! Please Help!

Question

Every time I think I have this figured out, I get stuck again. Everything has worked fine with my network for years, now problems.
I am using a DSL modem from SBC Global connected to Airport Extreme. I then have 2 laptops that access the network.
In re-installing everything I think something got messed up.
The only way I can get the laptops to find internet over the wireless network is by the DSL Modem being plugged into the LAN port. But then I can't get both laptops on the network at the same time. (I think it's only sending out one IP and whichever laptop gets it first, the other one says that the IP is in use.)
When I run the Airport Admin Utility it tells me that I should have the modem going into the WAN port, but when I do that, I get no internet over the wireless at all (but do not get the IP error message on the 2nd laptop).
When I try and change the settings in the "Network" Menu... I have it checked to "Distibute IP addresses" and have the top choice set (Share a Single IP). When I try to change to the 2nd choice (Share a Range of IPs) it wants me the change the "Internet" menu to a static IP address, which I think I can't because SBC Global throws out dynamic IP's (if I have that right - meaning everytime I click re-new DHCP lease, I get a new IP).
In the words of Charlie Brown, "UGGGGHHH!". Why is this always so hard.
Please help! Thanks!
Powerbook G4 1.67 Ghtz   Mac OS X (10.4.8)  

Answer 1

When I run the Airport Admin Utility it tells me that I should have the modem going into the WAN port, but when I do that, I get no internet over the wireless at all (but do not get the IP error message on the 2nd laptop).
The correct network configuration should be something like the following:
DSL modem > (Ethernet cable) > [WAN port] AEBS > (wireless) > wireless clients
If your DSL ISP does NOT require PPPoE for connectivity, then use the following to double-check your AEBS's settings...
Modem/Router Power ReCycling
- Power-off the DSL modem & AEBS. (Wait for at least 30 minutes. If possible, leave the modem off overnight.)
- Power-on the DSL modem; Wait at least 30 minutes.
- Power-on the AEBS; Wait at least 5 minutes.
Setup the AEBS
Temporarily connect your computer directly (using an Ethernet cable) to the LAN port of the AEBS, and then, check these settings:
AirPort tab
- Base Station Name: <whatever you wish or use the default>
- AirPort Network Name: <whatever you wish or use the default>
- Create a closed network (unchecked)
- Wireless Security: Not enabled
- Channel: Automatic
- Mode: 802.11b/g Compatible
Internet tab
- Connect Using: Ethernet
- Configure: Using DHCP
- WAN Ethernet Port: Automatic
Network tab
- Distribute IP addresses (checked)
- Share a single IP address (using DHCP & NAT) (enabled)