Wake-on-LAN

What it does: sends a Wake-on-LAN 'magic packet' (broadcast UDP) to power on a machine by its MAC.

Reaching another subnet: the broadcast box defaults to 255.255.255.255 (this segment). A picker offers each of this machine's local subnet directed-broadcasts, and for a subnet you're NOT on you can type its CIDR (e.g. 10.30.40.0/24) and 'Compute broadcast' to fill in that subnet's directed broadcast — a router set for 'ip directed-broadcast' can then forward it to wake a host on that remote VLAN.

Safe to run: yes — it only broadcasts a wake request; there's no reply, so 'sent' doesn't guarantee the host woke.

Reading results: n/a. Requirements: the target must have Wake-on-LAN enabled in BIOS/UEFI and its NIC, and be reachable by the broadcast you chose. Use the device's wired MAC.