On my Moto X, it's called something else: "Wi-Fi optimization". I tried turning it off, but still saw the problem. Then, I tried disabling something that's referred to by Apple users as "captive portals". Disabling that feature seemed to do the trick for me. However, I made those changes on Tuesday. Today, I decided to try turning them back on to see if I could reproduce the symptom: now, it won't fail. So, I'm still not sure what the magic fix is.