When sourcing a Wifi Router UPS, the most critical factor is Voltage Compatibility. Most routers operate on 5V, 9V, or 12V DC, so you must ensure the UPS supports the specific output required by your device; multi-voltage output models are highly recommended for versatility. Additionally, check the Battery Capacity (mAh or Wh)—a capacity of 8800mAh to 10400mAh is standard for providing 4 to 8 hours of backup time. Lastly, verify the Transfer Time, which should be 0ms (Online UPS) to ensure the router does not reboot during a power transition.