So, After messing around at the Apple store genius bar, and optus tech support.
THe 5G gateway hadn't downloaded the latest firmware. going to the browser admin page showed an outdated menu. THe new firmware is significantly different (and fancy looking) user interface.
The wifi encription was causing the devices to reboot as a security precaution. After changing both the 2.4 and 5 wifi settings to WPA2/AES encription it solved the rebooting issue, and now my home lights work aswell!