iPad 4 not connecting to WiFi network
I have two iPads in front of me - mine (iPad 3, WiFi only) and a friend's (iPad 4, WiFi and 3G). The iPad 4 has no data plan yet. Both iPads have iOS 6.0.1.
My iPad is and stays connected to my WiFi network (as well as my iMac and two MacBooks) but the iPad 4 looses the connection all the time and very often does not even join the network (message: "Unable to join the network xxx"). This is basically true for both of my networks (2.4 GHz and 5 GHz). It works somehow better for the 2.4 GHz network and is very bad with the 5 GHz network). Restarting the iPad does not help.
What I also notice is that the iPad 4 is seeing less available networks than the iPad 3 (but it always sees both of my networks).
Any idea what might be wrong here and how it can be fixed? I know there is already an iOS 6.0.2 but as far as I know it is only for the iPad mini and the iPhone 5 and anyway my iPads here say that the software is up to date with iOS 6.0.1 and an update is not possible.