I have a client with a Zyxel router. We just can't figure this out but it seems that there is something wireless on or off the network that is causing the router to reboot. When the wireless is switched off the up time just keeps rising, as soon as the wireless is switched on the router might stay on for 20 minutes then reboots.
Most of the devices on the network are Macs.
Does anyone have a similar experience?