classic W3 isn’t supposed to update unless you connect to bnet, so idk man
Classic game installers have to be downloaded from your account page which has a classic CD key registered. If you install classic War3, it should not update unless you connect to battle.net. The game is not online and doesnt care about your internet connection unless you do so.
Battle.net still provides the classic installers, there’s no need for any external third party links.