Connection Failed With Error 651: What It Is and How to Fix It

A variety of causes could be behind your internet connection error

A woman looking frustrated while trying to use Facebook Marketplace on her laptop.

AntonioGuillem/iStock/Getty Images Plus

The Error 651 error message is a common alert on computers running Windows 7 through to Windows 10. It typically occurs while trying to connect to the internet and is used to alert the user to the fact that an attempt at a connection to the internet has been unsuccessful, or an existing connection has been terminated.

How the Connection Failed With Error 651 Error Appears

The Error 651 message can vary depending on the actual cause of the connection problem, but it will always feature the following text:

Connection Failed With Error 651

While annoying, Error 651 is a relatively minor problem and shouldn’t cause a Windows computer to shut down or restart. It’s also incredibly unlikely you’ll be presented with the blue screen of death.

The Connection Failed With Error 651 message usually appears in a small pop-up text window, which can be quickly read and dismissed so you can work on tracking down the cause.

Cause of Connection Failed With Error 651 Errors

There are a variety of issues that can trigger a Connection Failed With Error 651 message, ranging from hardware and software issues to problems with your internet provider.

Known causes of Error 651 include a .SYS file being placed in the wrong location, the modem being set up incorrectly, corrupted registry files, an IP address conflict, and driver problems.

How to Fix a Connection Failed With Error 651 Error

Due to the number of potential causes of the Error 651 message, there are a variety of strategies you can try to fix this particular problem.

  1. Test the connection on another device. This is the easiest way to check if the problem is related to your Windows computer, your modem, or your service provider.

    If you can connect another device to the same internet connection, the problem lies with your computer. If you’re unable to connect anything else to the same connection, the problem has something to do with your modem, router, or provider.

  2. Try a different connection. Another way to pinpoint the cause of Error 651 is to try connecting to a different internet connection. If you can’t, the problem is your computer; if you can, the connection itself is to blame.

  3. Check for loose cables. A basic tip, but an effective one; make sure all of your power and connection cables are plugged in securely to your computer, modem, router, and wall.

  4. Reboot your modem and router. Rebooting your modem and router is an effective way to solve most common internet problems. Simply unplug both devices, wait a minute, then plug them back in.

    It may take a few minutes for a new internet connection to be made after plugging your router and modem back in again.

  5. Restart your computer. A classic tech tip that fixes a range of computer troubles, whether you’re using Windows 7, Windows 8.1, or Windows 10.

  6. Run the Internet Connections Troubleshooter. Windows 10 has a collection of built-in programs called Troubleshooters which can be used to scan and fix errors.

    To begin the Internet Connections Troubleshooter, open the Start Menu and select Settings > Update & Security > Troubleshoot > Internet Connections > Run the troubleshooter.

    Make sure your modem, router, and all associated cables are connected before running the Internet Connections Troubleshooter.

  7. Check for Windows updates. The Windows update process not only installs all of the latest features and security updates, but it also scans your computer, fixes errors, and downloads any files that may be missing or corrupted. To manually check for an update, go to Settings > Update & Security > Check for updates.

  8. Update your network adapter driver. Drivers are needed to make sure hardware is running correctly. Installing a newer one, if available, could solve your internet connection problems and stop that Connection Failed With Error 651 message from popping up.

  9. Disable antivirus software. Some antivirus software can prevent Windows computers from properly connecting to the internet. Pausing them or turning them off completely frequently fixes internet connection issues.

  10. Try these Windows 10 command prompts. In the Windows 10 taskbar search bar or from within Cortana, type "Command prompt" then select Run as administrator > Yes. Next, type in the following command prompts; after entering each one, press Enter to register it, then restart your computer and check the connection:

  • netsh int ip reset reset.log. This will reset the Windows networking stack.
  • Netsh interface tcp set global autotuning=disabled. This will disable autotuning.
  • regsvr32 raspppoe.sys. This will re-register the raspppoe.sys file.