Wake on LAN (WoL) is a networking standard that allows a sleeping or powered-off device to be awakened by a special network message called a magic packet. The protocol was co-developed by AMD and Hewlett-Packard in 1995 and is supported by virtually all modern Ethernet network adapters.
The TapHome template sends a WoL magic packet via UDP to a target device. It exposes a single push button — pressing it constructs the magic packet and sends it to the configured IP address. This is a write-only template with no polling or read-back capability, since Wake on LAN is a one-way protocol with no delivery confirmation.
Configuration
During template import, TapHome prompts for two parameters:
| Parameter | Description | Example |
|---|---|---|
| IP Address | Broadcast address of the target network | 192.168.0.255 |
| MAC | Target device MAC address (space-separated hex) | 12 34 56 78 9a bc |
The IP address should typically be the subnet broadcast address (e.g., 192.168.0.255 for a /24 network), not the target device’s unicast IP. Since the device is powered off, it does not have an active IP — the magic packet is broadcast and the target NIC recognizes its own MAC address in the payload.
The MAC address is stored as a module variable and used to construct the magic packet. It must be entered in space-separated hex format (e.g., 12 34 56 78 9a bc).
The target device must have Wake on LAN enabled in its BIOS/UEFI settings and on its network adapter. Without this, the magic packet will be sent but the device will not wake up.
Target device preparation
Wake on LAN requires configuration on the target device before it will respond to magic packets:
- BIOS/UEFI — enable Wake on LAN (typically under Power Management or Network Boot)
- Operating system — enable WoL on the network adapter:
- Windows: Device Manager > NIC properties > “Wake on Magic Packet”
- Linux:
ethtool -s eth0 wol g
- Power supply — the network adapter must receive standby power when the system is off
WoL works from ACPI sleep states S1 (Standby), S3 (Sleep), S4 (Hibernate), and S5 (Shutdown). It does not work from G3 (Mechanical Off) where no power reaches the network adapter.
Device capabilities
Wake button
The template exposes a single push button device. Pressing it sends a UDP packet containing the WoL magic packet to the configured IP address on port 9999. The magic packet consists of 6 bytes FF (synchronization stream) followed by 16 repetitions of the target MAC address — 102 bytes total.
There is no read-back or status polling. The button is write-only — it triggers the packet send and returns immediately. Since WoL is a one-way protocol, there is no confirmation that the target device actually woke up.
Additional capabilities
The WoL standard also defines a SecureOn password feature where a 4- or 6-byte password is appended after the MAC repetitions for additional authentication. Subnet-directed broadcast (sending to a specific subnet broadcast address like 192.168.1.255) can be used to reach devices across subnets if routers are configured to forward directed broadcasts. These capabilities can be added in a future template update.
Troubleshooting
Device does not wake up
- Verify that Wake on LAN is enabled in the target device’s BIOS/UEFI settings
- Verify that the network adapter has WoL enabled at the OS level
- Confirm the MAC address in TapHome matches the target device’s Ethernet adapter (not Wi-Fi)
- Check that the IP address is set to the correct broadcast address for the target subnet
- Ensure the target device’s power supply provides standby power to the network adapter
Wi-Fi devices
Wake on LAN is designed for wired Ethernet connections. Most Wi-Fi adapters do not maintain a link in low-power states, so standard WoL magic packets will not reach them. Some devices support Wake on Wireless LAN (WoWLAN), but this is a separate standard and may require different configuration.
Wake on LAN is a one-way protocol — there is no built-in mechanism to confirm whether the target device actually woke up. To verify, consider adding a separate network ping check or monitoring the device’s availability through another TapHome integration.