Status: You can connect to the school's address, but you can't connect to the school's server. Ping 222.27.192.73 in cmd shows that the request timed out.
Reason: IE is offline
Solution: Reset IE
In IE, click Settings->Internet Options->Advanced---->Reset, check Delete Personal Settings, and restart IE.
Experience: first check if ie is available, then log in to easyconnet when vpn is closed, then open vscode, and finally use vpn.