This is what I use. Once you set them up you can remotely restart your rigs from anywhere in the world. The work by using a relay to power on/off the motherboard using the switch inputs.

https://www.ebay.com/itm/WIFI-APP-USB-WatchDog-For-Mining-Miner-Rig-Crash-Auto-Recover-Reboot-Gaming-New/142872765557?hash=item2143e16475:g:5UkAAOSwO0Ra8Bms