In the event your voltage ranges are unstable (ie: power stays on, but the particular voltage amount may differ a whole lot through the 220V common), then I believe that's the type of circumstance exactly where an AVR is useful. A UPS device for the router and modem is additionally https://history-of-judo94826.wssblogs.com/33788967/getting-my-uninterruptible-power-supply-pdf-to-work