The CyberPower CP1500EPFCLCD is an excellent UPS ... then the Vertiv Liebert PSI 1500VA is definitely worth considering. Its three batteries will keep power-hungry devices running when the power ...

If all you want to power is the router (let's assume 12v 2a device), then the 1500va 700w ups I have should power it ... 700w+, also check brands recommended by others, such as Eaton or Cyberpower.