I have had the same problems with my wifi numerous times, where the note would not recognize the wifi, but all my other devices would.
This may seems to be a strange solution, but turning the wifi on and of, numerous times(lets say 30), seems to make it visible again. Also, after some time(4-5 month) it reverts back to not recognizing the device. This solution has worked for me each of 3-4 times it has happened