APC Back-UPS Pro (BX1000M) - routers and switches rebooting

[Anonymous user]

I've got a APC Back-UPS Pro (BX1000M).

I've got the following connected to it:

• Lower powered NAS
• VM server
• cable modem
• 8-port switch
• small router

The highest load I've seen is 27%, at under 200 watts.

I've got the USB cable run to the NAS and am using Network Utility Tools to shut it down on power loss, after 30 seconds.  I tested the UPS by pulling the power cable.  My NAS successfully shuts down gracefully.  Upon plugging the power back into the wall, and turning the NAS back on, the UPS goes back and forth between battery and A/C power. When I put the plug back in the wall, it stays on battery for a bit, then eventually goes online to A/C power.  It will then go back to battery after a bit, and finally back to A/C power.

The NAS and the VM server (the two x86 computers in this scenario) handle this fine.  However, the small, ARM-based devices (modem, switch and router) all reboot when the UPS switches back and forth between power and battery.

As a noob, am I missing anything?

Thanks