Accessing OnPremises Active Directory from WebRole running in Azure

I am trying to access the onpremises active directory from the web application running on Azure. We have selected Azure Connect as it best fits our requirement (authenticate user as well as fetch user information from Active Directory).

I have followed the steps provided in this link1 and link2, but still failing to achieve the goal.

Below is the method, I a trying to test if the onpremises Active Directory is reachable from Azure: DirectoryEntry.Exists("LDAP Path")

Below is the error I am encountering:

System.Runtime.InteropServices.COMException (0x8007054B): The specified domain either does not exist or could not be contacted.
at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)
at System.DirectoryServices.DirectoryEntry.Exists(String path) at WebRole1.MyLogInPage.btnSubmit_Click(Object sender, EventArgs e)

I can see the connect endpoint software is running fine without any connectivity issue, on the server running Active Directory and the endpoint group is properly setup.