1. Press Windows Key + Q, type troubleshooting, and pick the same from search results.
  2. Next click View all in the window so open which will take you to the All Categories option.
  3. Next, look for the Network Adapter option here to open Network Troubleshooter and follow the on-screen instructions to perform troubleshooting, at last you may came around following result.

As you can see in the image above, the troubleshooting report says The Diagnostics Policy Service is not running, and the troubleshooter was unable to fix this, although it has detected it. So in order to fix network issues due to this error, you can try the following steps:

The Diagnostics Policy Service is not running

  1. Open an administrative Command Prompt.

  2. Type the following commands one by one and press Enter key after each command:

  3. After executing both the commands, you’ll get The command completed successfully message. Close the Command Prompt window and reboot the machine, retry to connect the networks which are throwing trouble previously, this time you won’t face any issue. Let us know if it worked for you. How to troubleshoot Network & Internet connection problems may also interest you.