The error "The Realtek Network Controller was not found" indicates that your computer’s operating system (usually Windows) cannot detect or properly communicate with the integrated Realtek Ethernet adapter. This means you won’t be able to connect to the internet via an Ethernet cable.
This problem can stem from several causes, ranging from simple software glitches to more serious hardware failures. Here’s a comprehensive guide to troubleshoot and fix it:
1. Basic Checks and Power Reset
Check Physical Connections: Ensure the Ethernet cable is securely plugged into both your computer’s Ethernet port and your router/modem. Try a different Ethernet cable if you have one. Router/Modem Restart: Power cycle your router and modem. Unplug them from the power outlet for about 30 seconds, then plug them back in and wait for them to fully boot up. Computer Power Reset (Hard Reset): This can often resolve issues caused by a device getting stuck in a low-power "Deep Sleep" mode. Shut down your computer completely. Unplug the power cable from the back of the computer (and remove the battery if it’s a laptop). Press and hold the power button on your computer for 30-60 seconds. This drains any residual power from the motherboard components. Plug the power cable back in (and reinsert the battery). Power on your computer and check if the network controller is detected.
2. Device Manager Troubleshooting
This is where you manage your hardware devices and their drivers.
Check for Hidden Devices: Right-click the Start button and select "Device Manager". In Device Manager, go to "View" in the top menu and select "Show hidden devices". Expand the "Network adapters" section. Look for any Realtek Ethernet adapters. If you find one, it might be disabled or have a yellow exclamation mark indicating an issue. Scan for Hardware Changes: In Device Manager, click on "Action" in the top menu. Select "Scan for hardware changes". This will prompt Windows to re-scan for connected hardware and might detect the network controller. Enable the Device: If the Realtek adapter appears but is disabled (indicated by a down arrow icon), right-click on it and select "Enable device". Update/Reinstall Driver: If the Realtek adapter is listed (even with a yellow exclamation mark), right-click on it and select "Update driver". First, try "Search automatically for drivers". If that doesn’t work, right-click again and select "Uninstall device". Important: Check the box that says "Attempt to remove the driver software for this device" if it appears. After uninstalling, Restart your computer. Windows should automatically try to reinstall the driver on reboot. If not, go back to Device Manager and "Scan for hardware changes" again. Download Driver from Manufacturer’s Website: This is often the most reliable method. You’ll need another internet-connected device (another computer, phone, tablet) to download the driver. Go to the Website of your computer’s manufacturer (e. g., Dell, HP, Lenovo, Asus, Acer, MSI, Gigabyte, etc.). Navigate to their Support/Downloads section. Enter your Computer’s model number (or service tag/serial number for pre-built systems) or your Motherboard model number (if it’s a custom-built PC). Find the "LAN" or "Ethernet" driver for your specific Realtek chip and your version of Windows (e. g., Windows 10 64-bit). Download the driver installer (usually an. exe file) to a USB drive. Transfer the driver to your problematic computer and install it. Restart your computer after installation.
3. Power Management Settings
Sometimes Windows can turn off the network adapter to save power, leading to it not being found.
Open Device Manager. Expand "Network adapters". Right-click on your Realtek Ethernet adapter (if it appears) and select "Properties". Go to the "Power Management" tab. Uncheck the box that says "Allow the computer to turn off this device to save power". Click "OK". Restart your computer.
4. BIOS/UEFI Settings
The Ethernet controller might be disabled in your computer’s BIOS/UEFI settings.
Restart your computer. During startup, repeatedly press the key to enter BIOS/UEFI settings (commonly Del, F2, F10, F12, or Esc). The specific key varies by manufacturer. Once in BIOS/UEFI, look for sections related to "Integrated Peripherals," "Onboard Devices," "Advanced," or "Northbridge/Southbridge". Find an option like "Onboard LAN," "Ethernet Controller," "Integrated NIC," or similar. Ensure it is set to "Enabled." Save changes and Exit BIOS/UEFI. Your computer will reboot.
Reset BIOS to Defaults: If you’re unsure which setting to change, you can try resetting the BIOS to its default settings. Look for an option like "Load Setup Defaults" or "Optimized Defaults." Be cautious, as this will reset all custom BIOS settings.
5. Windows Network Reset / Winsock Reset
These can help if there are underlying network configuration issues.
Network Reset (Windows 10/11): Go to Settings > Network & Internet > Status. Scroll down and click on "Network reset". Click "Reset now" and confirm. This will reinstall all network adapters and reset network components. You’ll need to re-enter Wi-Fi passwords if applicable. Restart your computer. Winsock Reset (Command Prompt): Right-click the Start button and select "Command Prompt (Admin)" or "Windows PowerShell (Admin)". Type the following command and press Enter: netsh winsock reset Type this command and press Enter: netsh int ip reset Restart your computer.
6. Consider Hardware Failure
If none of the above software-related solutions work, it’s possible that the integrated Realtek Ethernet chip on your motherboard has failed.
Test with a USB Ethernet Adapter: The easiest way to confirm a hardware failure is to purchase an inexpensive USB to Ethernet adapter. If this adapter works and provides internet access, it strongly suggests your onboard Realtek controller is indeed faulty. PCIe Ethernet Card: For desktop PCs, you can also install a separate PCIe Ethernet expansion card, which plugs into a PCIe slot on your motherboard.
By following these steps systematically, you should be able to identify and resolve the "Realtek Network Controller was not found" error.