Error 6021 is a general server timeout error that occurs when it takes too long to receive a response from the server when attempting to connect. This usually can be caused by latency from your local network or interference from antivirus/firewall software.
Please first temporarily disable any antivirus/firewall software you are running and attempt your connection again. If the issue persists, we would recommend attempting to connect using an alternative protocol such as PPTP or L2TP to see if you experience similar issues.
Our support team can work with you further to determine if the error is being caused by latency or other issues. If the issue persists after the steps above, please contact our support team here.