Error 651 | Fix Connection Failed with Error 651 in Windows

It is possible that you might have faced error 651 on your computer if you are a windows user. It is a common problem faced by many windows users (Especially windows 7 users). So before we get into the topic, first lets see when this error occurs.

When Error 651 occurs ??

Error 651 usually occurs when we try to establish internet connection using a broadband connection and if this problem occurs then you might see an errors which displays Error 651 : The modem (or the other connecting device) has reported an error and usually the message will be titled as “Connection failed with error 651”.

So how to solve this error ? well there is no official solution to fix this error, but 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 this error.

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How to Fix Connection Failed with Error 651 in Windows

I have compiled a list of solutions that I have collected from various forums and help centres, all these solutions worked for many peoples and I'm sure that one of below solution will definitely work for you. So lets start from basic troubleshooting step to advance one.

1 - Reconnect Your Router or Other Connecting Device

This is the most basic troubleshooting step, One can simply solve this error by reconnecting the internet connecting device. So if you are using router then simply turn off your router and after 5 minutes turn it on or if you are using LAN connection then unplug the wire and plug it back.

2 - Reset TCP/IP On Your PC

Resetting the windows networking stack can solve error 651 and luckily windows 8/7/Vista comes with a built-in tool you can use to do this just follow the below steps.

• Launch command prompt with administrative right.
• Copy the command given below and hit enter

netsh int ip reset reset.log 

• Restart your computer and hopefully the problem will be solved.

3 - Recreating Dial Up Connection

Your internet connecting device might get hanged during the connection. So recreating your dial up connection can fix this issue. So simply right click your Dial Up or Broad band connection and select create copy and then delete your existing connection. Confused ? Just follow the step by steps guide given below.

• Open Network & Sharing Center and click on Change Adapter Setting.
• Now right click your broadband or dial up connection and select Create Copy.

• This will create a copy of your existing connection.
• Now simply delete your old connection and redial the new connection.

4 - Disable Auto Tuning Feature

If you are using a router then this method can do the magic, Follow the below steps to disable auto tuning feature.

• Launch command prompt with administrative rights.
• Copy the below command and paste it in command prompt

Netsh interface tcp set global autotuning=disabled

• Now just try to restart/reconnect your internet connection.

5 - Disable IPv6 of your Internet Connection

This solution worked for many users. You can simple disable IPv6 to fix this error. Follow the below guide to disable IPv6.

• Open Control Panel.and select Network & Internet.
• Further choose Network & Sharing Center.
• Now click on your active network connection.

• Select Properties and switch to Networking tab.

• Untick/Uncheck Internet Protocol version 6 (TCP/IPv6) and click on Ok.

6 - Reinstall Network Adapter 

This is the most working troubleshooting step when it comes to internet connection problem. You can simply reinstall the network adapter to fix Connection Failed with Error 651 problem. Just follow the below guide to reinstall network adapter.

• Go to start and search for devmgmt.msc.
• Double click it to launch device manager, Now look for Network Adapters Category and click the "+" icon it's left.

• Now right click the first network adapter and select uninstall.
• Restart your computer and your network adapter will get automatically reinstalled.

7 - Perform Clean Boot

If there is a problem in windows services then performing a clean boot can fix your problem, to perform a clean boot we simply need to disable all other services. Simply follow the below guide to perform a clean boot on your computer.

• Go to start and search for msconfig.exe 
• Click it to launch windows configuration.
• Now under general tab click on Selective startup and select Load startup items

• Now switch to Services tab and check Hide all Microsoft services.
• After that just click on Disable all to disable all other services.

• Now simply just restart your pc to perform a clean boot.

I hope the above solutions helped you in solving error 651, If not then it might be your ISP's issue, you should immediately contact your internet service provider (ISP) and report this issue.