I solved it by disabling the Stealth mode in with a registry tweak vi AD GPO: [URL=‘http://www.fogproject.org/wiki/index.php/Troubleshooting_Host_Management_Showing_Hosts_as_Down#Windows_Vista.2F7_.28Windows_Firewall_with_Advanced_Security.29’]A[/URL]rticle [URL=‘http://www.fogproject.org/wiki/index.php/Troubleshooting_Host_Management_Showing_Hosts_as_Down#Windows_Vista.2F7_.28Windows_Firewall_with_Advanced_Security.29’]HERE[/URL]
I went mad enabling / disabling firewall, logging packets, changing rules … That made it work. If you are not in an Active Directory, add the registry key, changing DomainProfile for PublicProfile, StandardProfile or PrivateProfile, depending of your needs.