I have an Unleashed at home that randomly reboots rather frequently. The longest it worked was around 5 days. It is powered by its genuine power adapter, connected to my net provider's HGW by a CAT5e cable of 3m. It gets its static IP via DHCP.
After reboot logs are lost. I set up an ftp server on my local net (checked its working by hand ), but no logs transferred.
Working from home a lot and its painful to be broken off the net so frequently, many times in the worst moments.
Is this the only access point in your setup or do you have more ? Can you download support log of this AP and if other and add here to review ? You can yourself too verify the reason for reboot of any AP by downloading the support log and searching with "### Reboot Reason In Detail Recently ###" or simply "reboot". These filter would show your the exact reason of reboot and help diagnose further.