Wake on LAN Troubleshooting (Windows Edition)

🔍 Scanning Your Network

1. Download WakeMeOnLAN
2. Launch WakeMeOnLan: Run WakeMeOnLan.exe. No installation is required.
3. Initiate Network Scan: Press F5 to start scanning your local network. The tool will detect active devices and retrieve their IP and MAC addresses.
4. Adjust IP Range (if necessary): If the scan doesn't cover the desired IP range, press F6 to stop the scan. Then, press F9 or go to Options > Advanced Options to specify the correct IP address range.
5. Review Scan Results: Devices will be listed with their status—green icons indicate online systems, while red icons denote offline ones.

Note: The scanned device information is saved in the WakeMeOnLan.cfg file for future use. (NirSoft)

💡 Waking Offline Systems

1. Select Target Devices: In the main window, highlight the offline computer(s) you wish to wake.
2. Send Wake-Up Signal: Press F8 or choose File > Wake Up Selected Computers. This action sends a "magic packet" to the selected devices.
3. Verify Wake-Up: After a short wait, press F5 to rescan the network and confirm that the devices have powered on (indicated by green icons).

⚙️ Command-Line Operations

WakeMeOnLan supports command-line operations for automation:

• Wake a Specific Device:

WakeMeOnLan.exe /wakeup [ComputerName/IP/MAC]

Replace [ComputerName/IP/MAC] with the target's identifier.

• Wake All Devices in the List:

WakeMeOnLan.exe /wakeupall

• Wake Devices in a Specific IP Range:

WakeMeOnLan.exe /wakeupiprange [StartIP] [EndIP]

Replace [StartIP] and [EndIP] with the desired IP range.

Note: For these commands to work, the target devices must be listed in the WakeMeOnLan.cfg file. (NirSoft)

🛠️ Troubleshooting Tips

• Broadcast Address Configuration: If wake-up attempts fail, navigate to Options > Send The Wake-on-LAN Packet To... and try different broadcast address settings. Some systems respond better to specific configurations.
• Ensure Proper Hardware Settings:

• BIOS/UEFI: Enable Wake-on-LAN or equivalent settings.
• Network Adapter: In Device Manager, under the network adapter's properties, ensure that options like "Allow this device to wake the computer" and "Only allow a magic packet to wake the computer" are enabled.
• Fast Startup: Disable Fast Startup in Windows, as it can interfere with Wake-on-LAN functionality. (PCMAG)

If Wake-on-LAN (WoL) works immediately after a fresh boot of your network switches or gear, but fails after some time, this typically points to an issue with network gear forgetting MAC address mappings, dropping broadcast packets, or power management settings. Here's a breakdown of what might be happening and how to resolve it:

🧠 Why It Happens

After a fresh boot:

• Your switches remember the MAC address table and allow broadcast packets through.
• Devices that support WoL are reachable via their MAC address and broadcast magic packet.

After time passes:

• Switches may age out ARP or MAC table entries for sleeping/offline devices.
• Broadcast packets may be blocked, misrouted, or not forwarded to the sleeping machine.

🔧 Troubleshooting and Fixes

1. Enable Directed Broadcast (if possible)

Many switches and routers block broadcasts by default. Enable directed broadcast to the subnet (e.g., 192.168.1.255) if your switch/firewall allows it.

📝 On managed switches, look for settings related to:

>

* Directed broadcast forwarding
* IP helper address (for Layer 3 switches)
* Static MAC address binding

2. Set Static ARP or MAC Table Entries

Manually configure your switch/router to always remember the MAC address of the WoL target.

• On managed switches:

→ Add a static MAC address binding for the device to the switch port.

• On routers/firewalls:

→ Use a static DHCP reservation so the MAC/IP relationship never changes.

3. Ensure WoL is Configured Correctly on Target Device

• BIOS/UEFI:

✓ Enable Wake-on-LAN / PME Event / ErP → Disabled

• Windows NIC Settings: ✓ "Allow this device to wake the computer"

✓ "Only allow a magic packet"

4. Disable Windows Fast Startup

Windows Fast Startup can interfere with WoL.

• Go to: Control Panel > Power Options > Choose what the power buttons do > Change settings that are currently unavailable
• Uncheck Turn on fast startup

5. Use a Different Packet Mode

In WakeMeOnLan:

• Try using Unicast instead of Broadcast under: Options > Send The Wake-on-LAN Packet To > Unicast / Broadcast (Based On IP Address)

Unicast may work more reliably on switches that block broadcast traffic.

6. Keep the Switch “Alive” with Periodic Pings

You can ping the WoL targets regularly to keep their MAC entries active in the switch.

PowerShell script example:

while ($true) {
Test-Connection 192.168.1.101 -Count 1
Start-Sleep -Seconds 300
}

📌 Summary

Updated on: 10/12/2025