Download the DLL from this article.
Make a backup copy of the MiToken.ActiveDirectory.Library.dll inside the API installation directory:
C:\Program Files\Mi-Token\API Service
Stop the API service.
Copy the downloaded DLL to the API installation directory.
Declare the environment variable: MITOKEN_API_DEFAULT_DC
Set it to the FQDN of the domain controller.
Restart the API Service.
The patch will make the API service try to contact the server defined in MITOKEN_API_DEFAULT_DC if it is unable to locate the default DC on its own.