In the event your voltage concentrations are unstable (ie: power stays on, but the particular voltage level may differ a great deal from the 220V normal), then I feel that's the sort of scenario in which an AVR is helpful. A UPS unit on your router and modem is usually https://wax-co-pure-skin58136.rimmablog.com/32960705/new-step-by-step-map-for-uninterruptible-power-supply-ups