VPN on Windows 10: Selected authentication protocol not permitted on the remote access server

When trying to setup a VPN connection from Windows 10 to a VPN server that was managed by another company, I received the following error:

The remote connection was denied because the user name and password combination you provided is not recognized, or the selected authentication protocol is not permitted on the remote access server.

The username and password I had typed were correct, and these same credentials worked when connecting from Mac OS.

After checking the VPN protocol properties tab, I found that the remote server was requiring the use of MS-CHAP v2, a setting that was disabled by default. The company who had provided the VPN credentials had not stipulated that MS-CHAP v2 was a required protocol.

The following steps fixed the issue:

1. Setup your VPN connection as normal.
2. Open the 'Internet Options' settings by typing it into the start menu.
3. Click the 'Connections' tab
4. Click your VPN in the list and then the 'Settings' button.
5. Re-enter your username, password and domain in the boxes provided.
6. Click 'Properties'
7. Click the 'Security' Tab
8. Select the radio button titled 'Allow these protocols'
9. Select the checkbox titled 'Microsoft CHAP Version 2 (MS-CHAP v2)
10. Apply the settings in each of the windows by clicking 'OK'.

Try connecting to your VPN again and it should connect successfully.