100 Watts UPS or Inverter

Hi i need to buy 100 watts ups or inverter for modem router charger ...i already have mercury 350 UPS deisgned for Computer with dry battery which is backed by by normal or Desi UPS 800 watts ups but takes too many load on my desi ups even my pc is not running only in charging or on mode with router and modem so i need 100 watts UPS which do not restart my router and modem.

100 watt is a bit too much, most modems consume not more than 24W