I ran into the issue of having my 2wire router restart as soon as a wireless device was connected to it a few weeks ago. Meanwhile, any device connected via ethernet cable was perfectly fine. I went through the bulk of this thread, as well as another one, trying out all the work arounds and wireless setting tweaks. None of them worked for me. 

Luckily (I guess), my house had another 2Wire 2701 HG-B router that my sister had left behind. I replaced my router with hers, and instantly ran into the exact same issues. This left me really suspicious about whether the router itself was broken at all. 

I decided to borrow a 2Wire ac adapter from a friend and replaced my adapter. WIthout changing a single wireless setting, my wireless is now perfectly stable. 

The theory is the ac adapter was starting to break, but was still providing enough power to enable ethernet connections, but not enough to supply a consistent wireless signal. Getting a fully functional ac adapter fixed the issue. When you think about it, it kind of makes sense considering how poor the quality of the ac adapter is, hence this widespread wireless issue.