I'm having a bit of trouble setting up Exchange ActiveSync on some iOS devices. I can't seem to get the devices to connect to the Exchange box. When running the Remote Connectivity Analyzer I get 1 warning and 1 error which are displayed below: -

Testing HTTP Authentication Methods for [Our Server Address]/Microsoft-Server-ActiveSync/
The test passed with some warnings encountered.
Additional Details - The following authentication methods are enabled, but they aren't allowed authentication methods for this service. Methods: Negotiate, NTLM

Attempting the FolderSync command on the Exchange ActiveSync session.
The test of the FolderSync command failed.
Additional Details - Exchange ActiveSync returned an HTTP 500 response.

Any help greatly appreciated.