Normally, Error code 651 occurs when Windows 10 user tries to connect the network, which indicates that your modem (or other connecting devices) has reported an error and usually the message will be “Connection failed with error 651”. If you’re seeing this error, there’s nothing to worry about. It is most likely a simple configuration error that we can fix in less than ten minutes.

In such cases, you should first try to restart the Windows 10, router or modem. If the reboot is not working, in this article, there are some common troubleshooting methods which worked for many users, so I have collected some of the most working solutions that will help you to solve the Connection Failed with Error 651 in Windows 10.

How to Fix Connection Failed with Error 651 in Windows 10

Tips: To make things easier, Neptune SystemCare Ultimate, the PC optimization utility will check up whole computer problems and fix common errors, secures and optimizes your PC for maximum performance.

->Download and Install Neptune SystemCare Ultimate.

->Launch PC Checkup, wait and click on Fix.

->Restart your Windows.

Method 1 | Update network drivers

The network drivers help the network card to read and work. So, updating the driver is always the first thought. It is easy to do in Windows 10.

->Open Device Manager by pressing Win+X and choose Device Manager on the menu.

-> Look for Network adapters and expand.

->Right-click on the card and choose Update driver software…

->Choose the automatic option and let Windows find a suitable driver.

Method 2 | Disable IPV6

Disabling IPv6 to fix a lot of network issues within Windows, including error 651. IPv6 is a relatively new network protocol, but it can’t work with all the routers or networks. Therefore, we can turn it off temporarily.

->Go to Control Panel> Network and Sharing Center.

->Find and right-click Ethernet, and choose Properties.

->Go to Internet Protocol Version 6 in the center window and uncheck the box next to it. Click OK to apply.

Method 3 | Disable TCP tuning

TCP tuning is only utilized when your computer is connected to a router. If you connect directly to a modem, this will not work for you. If you are no tech geek, ignore and follow the steps.

->Open Task Manager by pressing Ctrl+Shift+Esc on the keyboard.

->Then choose File>Run new task, check the box under Create this task with administrator privileges, type cmd in the box and click OK.

-> Type or paste netsh int ip reset reset.log and press Enter. This wipes the log file for IP.

-> Type or paste netsh interface tcp set global autotuning=disabled and hit Enter. This disables TCP tuning.