How to configure WOL in BIOS to turn on machines via network

What is Wake on LAN and how it works in practice

Imagine being able to power on a computer or server located across the room or in an office without ever touching its physical power button. In practice, the feature known as Wake on LAN, or WOL, does exactly that: it allows a computer motherboard to remain in a low-power standby state, listening to the local network waiting for a specific command to wake the operating system. This command is popularly called a magic packet, a data sequence carrying the physical address of the network card that needs to be activated.

For this technological magic to happen, the network card never truly goes to sleep. It keeps an auxiliary circuit energized, consuming a negligible amount of electricity, solely to monitor incoming data traffic arriving via the connected cable. When the magic packet is sent from another device on the same network, the network chip recognizes the pattern and sends a direct electrical signal to the motherboard, simulating the exact moment a finger presses the power button on the computer case. This transforms everyday administration tasks into quick and automated processes.

The usefulness of this technology shines brightly in local server environments or development workstations. Instead of keeping powerful computers consuming energy and generating heat through the night, you can shut them down completely at the end of the workday and schedule a script or application to wake them only when a backup or heavy processing routine needs to run. To understand how the infrastructure ecosystem works in an integrated way, it is worth checking our guide on how to configure a VLAN on a managed switch via console, which helps isolate these devices on the network.

Preparing the ground: physical prerequisites on the motherboard

Before tweaking any software settings, it is important to understand that not all hardware supports this feature in the same way. Wireless network cards, or Wi-Fi adapters, rarely offer a reliable Wake on LAN experience due to how wireless power management handles sleep states. In the vast majority of production scenarios, WOL requires a traditional wired connection using Ethernet network cables plugged directly into an onboard motherboard network port or a dedicated PCI Express network card.

Another crucial detail involves the computer's power supply unit. Old or poorly made power supplies might fail to supply the correct five-volt voltage on the standby line, technically known as the +5VSB pin, which is the power responsible for keeping the network card circuit alive while the main computer is shut down. Additionally, if your network card has link indicator LEDs that remain lit even when the computer is completely powered off and plugged into the wall, that is usually an excellent visual sign that the card is receiving the necessary standby power.

Finally, ensure that the network cable is firmly plugged into both the computer and the central router or switch. During shutdown, the network port speed negotiation should drop to a low-power mode without dropping the physical link. Otherwise, the card will become completely isolated and unable to listen to any external signal. If you manage packages and updates frequently in Linux environments, keeping the system organized is just as important as the physical layer; therefore, we recommend reading about how to clear Apt cache on Ubuntu and free disk space to keep your servers optimized.

How to enter BIOS and enable power management features

The first practical step to unlock the feature happens before the operating system even boots, directly inside the motherboard firmware interface. To access this screen, reboot or turn on your computer and repeatedly press the key designated by the manufacturer, which is usually Delete, F2, F12, or Esc depending on the motherboard brand. Once inside the interface, the layout can vary significantly among traditional manufacturers like ASUS, Gigabyte, MSI, or ASRock, but power configuration menus usually follow a very similar logic.

Look for sections with names like Power Management, Advanced Power, ACPI Configuration, or Integrated Peripherals. Within these tabs, you will need to search for specific terms related to remote triggering. The most common names include Power On By PCI-E, Wake On LAN, Resume On LAN, PME Event Wakeup, or ERP Setting. The ERP or EuP setting, aimed at extreme power savings under European guidelines, is often the biggest enemy of WOL: if this option is enabled, the motherboard completely cuts power to auxiliary ports upon shutdown, making remote waking impossible.

Below are the essential steps to perform this basic configuration directly within your computer's firmware interface.

1. Reboot the computer and repeatedly press the BIOS access key until the main control panel appears on screen.
2. Navigate through the tabs using your keyboard arrow keys until you locate power settings, ACPI management, or advanced features.
3. Locate the Wake on LAN, PME Wakeup, or equivalent option, changing its state from disabled to enabled.
4. Ensure you disable any extreme power saving modes, such as ERP Ready, which prevents powering the network card.
5. Save the changes by pressing the standard save key, usually F10, and allow the system to reboot normally.

Configuring the operating system to keep WOL active

With the BIOS properly configured, the next step is ensuring the operating system does not disregard these instructions when shutting down. Modern systems like Linux feature advanced power managers that can completely cut power to peripheral devices during shutdown to save a few milliwatts of electricity. To prevent this unwanted behavior, we need to adjust network interface parameters directly via the system terminal.

In the Linux ecosystem, the standard tool to check and modify the Wake on LAN state is the ethtool utility. With it, you can check if the network card is set to listen for the wake signal and enforce this policy persistently. To complement this knowledge and deepen your systems administration skills focused on remote booting, also check our detailed guide on how to configure Wake on Linux command line to turn on Linux servers.

Below is a practical example of commands executed in the terminal to verify and enable the feature on the main operating system network interface.

# Find the name of your active network interface with ip link or ifconfig
# Let's assume the interface name is eth0

# Check the network card's current WOL support
sudo ethtool eth0

# Change the configuration to enable Wake on LAN via magic packets (letter g)
sudo ethtool -s eth0 wol g

# Confirm that the change was successfully applied by checking the Wake-on field
sudo ethtool eth0

Testing remote triggering and troubleshooting common failures

With everything configured in the BIOS and operating system, the moment of truth arrives: shutting down the machine and trying to bring it back to life from another computer connected to the same local network. To perform the test, you need to find out the MAC address and IP or broadcast address of the machine to be powered on. On the destination machine, open the terminal and run network commands to note down this vital information before shutting it down completely.

From a second computer or smartphone on the same Wi-Fi network linked to the same router, you can use command-line utilities to send the magic packet. On Linux or macOS, packages like wakeonlan can be easily installed via standard package managers. If the computer does not turn on right away, check if the local firewall is blocking the UDP port used or if the router isolated LAN ports, preventing direct communication between local devices.

Below is an example command used to send the magic packet by providing the physical address and network broadcast address.

# Install the wakeonlan tool if it is not yet present on your system
sudo apt install wakeonlan

# Send the magic packet providing the MAC address of the destination machine
wakeonlan AA:BB:CC:DD:EE:FF

# If you need to specify a specific broadcast address for your subnet:
wakeonlan -i 192.168.1.255 AA:BB:CC:DD:EE:FF

Final considerations on automation and WOL maintenance

Configuring Wake on LAN transforms the routine of anyone managing home servers, test labs, or high-performance workstations, eliminating energy waste without sacrificing operational agility. Although the process requires attention to specific details in the BIOS, operating system power management, and physical cabling integrity, the gains in convenience and efficiency amply reward the initial diagnostic and configuration effort.

Maintaining clear documentation of MAC addresses and network restrictions for each piece of equipment immensely simplifies the creation of automated startup scripts. With the infrastructure ready and tested, you gain the freedom to trigger your computing resources on demand, ensuring a modern, economical environment fully prepared to respond to your commands at any time.