Airport Express DNS(?) Issue

[RogerWilco6502]

So I just configured an AirPort Express (802.11n 1st Gen) as an access point to use with my older Macs. It configured fine and can be connected to, but I can't seem to access anything when connected to its network. Not the router, not Google, not even the AirPort Express itself.

Do you know what might be causing this issue? I thought it might be DNS, but I'm not so sure given it can't connect to anything.

I can ping it from the main network though.

 

[RogerWilco6502]

A little update: It looks like any device connecting that can support WPA/WPA2 is fine, which means that, even though I set it to WEP and it appears as such on the configuration page, it is actually WPA/WPA2. What's strange is that my G4 can connect to it, it just can't get an IP address and therefore won't work.

What is the deal with this and how can I fix it?