Launcher won't start game when no internet connection

Have a private server running for a children's library program, and the laptops used to connect to the server (running on a separate laptop connected to a router, etc.) will not start the game from Launcher when connected to the private network. The private network does not offer the computers internet connection. 

When the laptops are connected to a network offering Internet, the game starts and we are able to switch to the private network after. 

Attached is the Launcher Error Log