Base from the description of your problem it seems that the issue here is not with your Netopia wireless adapter but with your 2wire wireless router, because the 2wire is the one responsible to broadcast the wireless signal so your Netopia can pick it up.
So what you can do here is to reset the 2wire router by pressing the reset button of it its a small hole there , then you will need to reconfigure that and it will be better if you do that with the ATT people so they can tell you how to reconfigure the router.
Answers & Comments
Base from the description of your problem it seems that the issue here is not with your Netopia wireless adapter but with your 2wire wireless router, because the 2wire is the one responsible to broadcast the wireless signal so your Netopia can pick it up.
So what you can do here is to reset the 2wire router by pressing the reset button of it its a small hole there , then you will need to reconfigure that and it will be better if you do that with the ATT people so they can tell you how to reconfigure the router.