Using 3.0.0.4.206 firmware, the guest network is at best flaky and at worst a nightmare. If you just enable guest1 on 2.4 or 5gHz, it works OK as long as you don't mind having an open guest. But, not only (as the other poster mentioned) is it true that modifying those parameters actually changes the parameters for the non-guest networks, but it also leaves the AsusGuest ssids active. Even more, messing with guest 2 got it confused enough that I felt like I ought to reboot. At that point, the router had actually lost all its settings. Ugh!! If I had the source code, I am pretty sure I would find that there's a mismatch in the index into a table and/or an SSID table that's too small.
I do not know what the f**k in think Asus, but Padawan not hide the source code. Why is it still just did not copy is beyond my comprehension. And we all works, and soon also added IPv6