After the installation of Ivanti Antivirus, clients cannot connect through Direct Access.
Note: Ivanti Antivirus uses the Kaspersky Endpoint Security engine.
More details about Direct Access from Microsoft: Manage Remote Access )
To solve this problem please add 'svchost.exe' to Trusted Applications list and disable port 443 monitoring for it.
More about Exclusions for Applications: Chapter 2. File System Protection by Kaspersky