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Wake-on-LAN: wake your PC on the local network.

Wake-on-LAN can turn a sleeping computer into a machine ready to control, but it's a local-network signal: today it wakes within the same network, not by powering the machine on from anywhere on the internet. And it only works well when hardware, system and network all agree.

June 3, 2026 · 6 min

What NodalDesk sends

NodalDesk uses the standard mechanism: a magic packet with six FF bytes and the machine's MAC repeated sixteen times. That packet is sent over UDP broadcast, usually to 255.255.255.255 and port 9.

The server code gets the MAC of the primary IPv4 interface when it can. If it can't find it through Node's network API, it tries to read it with ip link show. It also computes the broadcast address from the IP and netmask.

What needs to be ready

WoL won't wake a machine that has fully cut the network card. Check three layers: BIOS or UEFI, operating system and physical network.

In BIOS/UEFI, enable Wake-on-LAN or an equivalent wake-on-network option.
In the operating system, allow the network interface to wake the machine.
Use Ethernet if you want reliability. WoL over Wi-Fi depends heavily on hardware.
Make sure NodalDesk knows the host's MAC.

Who sends the packet on your network

The Wake-on-LAN packet has to leave from INSIDE your local network. Today that piece is any NodalDesk node you leave powered on in that same network: it keeps presence, reports status and relays the magic packet to the sleeping machine. A dedicated system service that does this with no graphical session is part of the product direction, not yet a separate piece you install.

That's why the honest reach today is the local network: from the internet you can't launch a WoL broadcast straight into your private network. To wake a machine you always need a piece inside that same network to send the local packet; without it, there's no real remote power-on.

Waking from Android

The Android app has its own helper. It normalizes the MAC, checks that the phone is on Wi-Fi and sends the packet to port 9. Then it waits a few seconds and checks whether the server responds, to offer the connection.

If Android tells you it needs Wi-Fi, it's not a UI whim: the local WoL broadcast makes sense within a local network, and some Androids filter broadcasts unless specific measures are taken.

When it doesn't work

Start with the basics: try the PC suspended, not fully powered off; use a cable; confirm the MAC is the right card's; check power-saving options. Remember that the wake happens within the local network: if you want to launch it from outside, you need another machine already on in that same network to send the packet for you.

Wake-on-LAN guide Common problems