You want to know whether Windows Defender Application Guard of Windows 10 is compatible with Symantec Endpoint Protection (SEP) 14.x.
Windows Defender Application Guard is not compatible with SEP 14.x because it is based on Hypervisor Code Integrity (HVCI) technology that SEP 14.x does not support.
For more information, please see Endpoint Protection support for Windows 10 updates and Windows Server 2016 / Server 2019.