You can use your iPhone to wake your Mac, provided both are on the same local network.
If you need to wake your Mac, you usually will simply go to it and tap the keyboard or click the mouse; however, there may be times when the Mac may be out of reach, such as if it's a server in a locked closet. Granted, as a server you might not want to set the system to go to sleep, but there may be similar instances where a system is inaccessible and you need to wake it up.
Waking a system via the network uses a technology called Wake on LAN, which can be configured in your Mac's system preferences. This allows your system to be woken from sleep or standby modes by a special network datagram called a magic packet. In general, this is done to wake one Mac with another on the same network; however, you can also use it for any device that can send a magic packet, including your iPhone.
To use this, you will first need to know some information about your Mac, and ensure it is set up to be woken through the network. This information includes your Mac's physical MAC address, and optionally the IP address of the system:
Note that this process will require your Mac to be on the same network as your iPhone, so this cannot be done over the Internet. If the process does not work, then double-check that you have the right MAC address for your Mac's active network port. You can also try resetting your router, and checking its settings to ensure Wake On LAN features are allowed (sometimes there may be settings that block this).
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