When connecting to the Internet via a high-speed connection using the PPPoE protocol on operating systems such as Windows 7/8/10, the user may experience error code 651. In Windows XP, this error was code 678, and in Windows Vista - code 815.

An error like this is usually associated with improper operation of equipment on the client or provider side. It may also appear due to incorrect operation of Windows services. It is worth noting that reinstalling Windows, which users often resort to in case of various kinds of “fatal” errors, in this case will not lead to a positive result and will not be justified. At the very least, you should first try to solve the problem in less radical ways.

Creating a new connection

The first thing you should do when you encounter error 651 in Windows 7/10 is to create a new Internet connection. This way you will eliminate possible errors in the operation of system services. But before you create it, you should restart your computer. Next, go to the “Control Panel”, open the “Network and Sharing Center” section and select the “Set up a new connection or network” item.

In the next step, select the desired connection type – High-speed (PPPoE).

We carefully enter your network access data - login and password. Upon completion of all actions, click the “Connect” button.

If the connection fails again and error 651 appears, then you should look for other causes of the problem.

Two network cards

There are situations when a computer has two network cards to which different networks are connected. For example, you have the Internet connected through one card, and your local home or intra-house network through another. In the case of two network cards, you should disconnect one of them and check the Internet connection.

Go again to the “Network and Sharing Center” and on the left side of the window open the “Change adapter settings” section.

Right-click on the local network connection that you want to disconnect, and select “Disconnect” from the context menu. After this, we try to connect to the Internet. If you do not know which adapter the Internet is connected to, then simply disconnect first one and then the other adapter. The appearance of error 651 after all the manipulations performed will indicate that the cause needs to be looked for elsewhere.

Error 651 occurs due to Windows 7/10 firewall

Often the cause of connection failure is a firewall - a special program that controls access to the network for various applications and services. The Windows firewall or firewall may be built into the antivirus program installed on your computer. In order to exclude the firewall as a possible culprit for error 651, it must be disabled.

First, deactivate the built-in firewall in Windows. To do this, go to the “Control Panel” and open the “Windows Firewall” section. On the left, click on the “Turn Windows Firewall on or off” menu. Set the switch to the “Disable” position everywhere and click the “OK” button.

If in the “Windows Firewall” section you see a warning message that control of the settings has been transferred to the antivirus program, then you will have to disable the firewall through the antivirus. In ESET Smart Security, to manage the firewall, you need to go to the Settings page.

After all the steps, we check whether our high-speed connection is working or not. If it fails again with error 651, move on.

Error 651 when connecting to the Internet via a router

At the next stage, we proceed to check the hardware for faults. First, disconnect and reconnect the network cable into the network card slot. The same must be done if you are using a router or router to access the network. We reconnect all network cables on the router and restart it by turning off and then on again the power.

If the problem still persists, then go in and check the router settings. To do this, launch a browser (Internet Explorer, Opera, etc.) and enter in the address bar: 192.168.0.1 or 192.168.1.1. Next, if the device asks for a username and password, enter them (the factory login/password is indicated in the documentation for the router). After this, the router's web interface will open. Here you should open the Internet or WAN section. The router operating mode should be in the Bridge position so that you can start the Internet connection from the computer yourself. If the router is operating in a different mode, then error 651 will always appear.

Many routers and routers allow you to configure an automatic connection to the Internet in the router itself, without the need to create this connection on your computer. Step-by-step instructions for creating the same PPPoE connection should be given in the device manual. Below we have provided a snapshot of the TP-Link router interface demonstrating the creation of a connection. As you can see in the figure, to go to the desired page you need to select the WAN item in the “Network” section. Next, we simply enter the data provided by the provider, as if we were doing it in a Windows 7/10 environment.

Updating network card drivers

It would be a good idea to update the network card drivers by downloading the software suitable for the operating system you are using from the website of your board manufacturer. You can find out the model of the network card in the “Device Manager”, which opens through the “Control Panel”.

In the list of devices, find and expand the “Network adapters” section, the information you are interested in will be indicated there. For laptop owners, you will have to find a driver on the manufacturer’s website based on the model of the laptop itself, which is somewhat simpler.

Failure on the provider side

In a situation where everything works as it should, but Internet connection error 651 remains, you should look for problems on the provider’s side. Usually all you need to do is call support, describe your problem and ask them to check the line to your port. After some time you will be informed about the results of such a check. If it turns out that everything is fine on the telecom operator’s side, then you can ask their specialists to check the settings on your computer.

Solving the issue by reinstalling Windows 7/10

If possible, try creating a connection on another computer or laptop. If everything works out there and access to the Internet is successful, then the problem is in the operating system itself and, most likely, you will have to reinstall Windows.

Before reinstalling, log into Windows in safe mode and download drivers. To do this, when you turn on the computer, even before the splash screen appears, you should press the F8 key, after which a window for selecting boot options will appear on the screen, where you can select the desired item. There is a possibility that in safe mode the connection will still be established, and after the next boot of the OS in normal mode, error 651 will disappear. If the attempt is unsuccessful, there are no options - you need to reinstall Windows.