Authentication or 'auth' failures on Windows happen for a number of reasons, either relating to the password itself or the device count you have been connected to.
- Try to change your password, log out from the NordVPN app and then log back in. Change your password here: https://my.nordaccount.com/reset-password/.
- If the issue persists, make sure you have no more than 6 devices connected simultaneously with one account. If yes, disconnect one of the devices.
If that does not help, reinstalling the application should:
- Go to Control Panel > Uninstall a Program / Programs and Features.
- Locate "NordVPN", "NordVPN network TAP" and "NordVPN network TUN" instances and remove them if they appear on the list.
- Restart the computer.
- Go to https://nordvpn.com/download/, download the NordVPN app, and go through the setup steps.
