A new separate Sandbox server to test Order of War is already available for download, and do note the old Sandbox server will not update!
The current Sandbox server will not update because the test for the new game mode will be performed in a separate server and its called Sandbox 2.
Its important to remember, only accounts that have been accepted for the Sandbox 2 Test, will be able to download and login once the server is online!
If the application is approved, Wargaming will email you a special invitation granting access to the Sandbox. Check if your account has been accepted, and if yes, just open Wargaming Game Center, go to All Games and select Install Game by ID and enter the following code:
The server will open between 21 January, during the afternoon, through January 28, 2021.