Solved: Connection Failed error 651 in Windows 10/11

The Connection Failed Error 651 is a common Windows networking issue, usually occurs when we try to establish an internet connection using a broadband connection (PPPoE) connection. This error message means that Windows cannot establish a proper connection between your computer and the internet, preventing you from browsing online. The root cause of error 651 can vary, including software conflicts, driver issues, network misconfigurations, or problems with your ISP or modem/router. Here are several troubleshooting methods to resolve this error and establish an internet connection on your PC.

How to Fix Connection Failed Error 651

Mostly, you see this error when you try to connect or share your broadband connection with one or more devices. Several factors can trigger error 651, network misconfigurations, or problems with your ISP or modem/router are common.

• Incorrect Network Configuration – Misconfigured network settings can prevent the connection from being established.
• Corrupt or Outdated Network Drivers – Faulty drivers can cause connectivity issues, making it essential to keep them updated.
• Conflicts with Network Services – Background services, such as Windows updates, security software, or VPNs, may interfere with internet access.
• Damaged System Files – Corrupt Windows system files may prevent the PPPoE connection from working properly.
• ISP or Modem Issues – Sometimes, the problem is caused by an issue on the ISP’s end, a faulty modem, or a bad internet line.

Restart Your Modem and Router

Power cycling your modem and router is the simplest and often most effective way to resolve temporary network glitches. Restarting refreshes the connection between your ISP and your device.

• Turn off your modem and router.
• Unplug them from the power source and wait for 5 minutes to clear network cache.
• Plug them back in and turn them on.
• Allow the devices to fully reboot and try reconnecting to the internet.

Disable and Re-Enable the Network Adapter

If your network adapter is experiencing issues, disabling and re-enabling it can help reset the connection. This method forces Windows to reload the network adapter, eliminating any minor software glitches affecting connectivity.

• Press Win + X and select Device Manager.
• Expand Network adapters to view the list of installed network devices.
• Right-click your active network adapter and select Disable device.
• Wait for a few seconds, then right-click it again and select Enable device.
• Try connecting to the internet again to see if the problem is resolved.

Create a New Dial-Up (PPPoE) Connection

If your broadband connection settings are corrupted, creating a new PPPoE connection ensures that your internet connection is properly configured with the correct credentials.

• Open Control Panel and go to Network and Sharing Center.
• Click Set up a new connection or network.
• Select Connect to the Internet > Broadband (PPPoE).
• Enter your ISP username and password, then click Connect.
• Test the new connection to see if error 651 is resolved.

Run Windows Network Troubleshooter

Windows has a built-in troubleshooter that can automatically detect and fix network-related problems. Running Network adapter troubleshooter, allows Windows to identify and resolve common networking problems without manual intervention.

• Press Win + I to open Settings.
• Navigate to Update & Security > Troubleshoot.
• Click Additional troubleshooters and select Internet Connections.
• Click Run the troubleshooter and follow the on-screen prompts.
• Apply any recommended fixes and restart your PC.

Update or Reinstall the Network Driver

Outdated or corrupt network drivers can cause connection failures, including error 651. Updating or reinstalling them ensures smooth connectivity. Update or reinstal the network driver, ensure you are using the latest driver version, and prevents compatibility issues that may trigger error 651.

• Press Win + X and select Device Manager.
• Expand Network adapters and locate your active adapter.
• Right-click your network adapter and choose Update driver.
• Select Search automatically for updated driver software.
• If the issue persists, uninstall the driver by right-clicking and selecting Uninstall device, then restart your PC.
• Windows will automatically reinstall the required driver upon reboot.

Also, you can visit the Device manufacturer website, download the latest available drivers for this device and install it.

Disable IPv6 of your Internet Connection

Some networks experience compatibility issues with IPv6, which may result in connection errors.

• Open Control Panel and go to Network and Sharing Center.
• Click on Change adapter settings.
• Right-click your active internet connection and select Properties.
• Uncheck Internet Protocol Version 6 (TCP/IPv6) and click OK.
• Restart your PC and check if the issue is resolved.

Reset TCP/IP and Network Settings

Again misconfigured network settings can block internet access. Resetting the TCP/IP stack restores default network configurations.

Open Command Prompt as Administrator and Run the following commands one by one:

netsh int ip reset
netsh winsock reset
ipconfig /flushdns

Once done, close command prompt, restart your computer and check if the connection is restored.