Could it be security settings on the router, an ASUS WL-520GC.
Maybe.
Why you don’t disable the security settings (encryption, password, etc..) just for testing purposes and test if you can connect to an open WLan using your AT100.
Do you use the WLan standard which is supported by AT100? As far as I know the device is working on 2.4Ghz means it support 802.11 B/G/N