Windows 8.1 Update IIS 8.5上的公共HTTP端口转发失败

Question

I have three Windows hosts on the same private LAN, each hosting an IIS default website. One host is running Windows 7 Pro, while the other two are running Windows 8.1 Update Version 6.3 (Build 9600).

Other computers on the local subnet can open the default website on each of the 3 hosts by entering each host's private IP address in a browser.

However, when I Port Forward port 80 on a gateway router in turn to each of the 3 hosts private IP address, then enter the public IP of the gateway router into a browser on a computer outside of the private network, only the Windows 7 host displays its default website.

When Port 80 is forwarded to either of the two Windows 8.1 Update hosts, the browser reports "This webpage is not available. Details: The host took too long to respond." Additionally, no record of the request appears in "C:\\inetpub\\logs\\LogFiles\\W3SVC1\\u_exYYMMDD.log" on the host.

All three hosts have their Windows Firewall Inbound Rule "World Wide Web Services (HTTP Traffic-In)" set to Profile: All, Enabled: Yes, Action: Allow, Override: No, Program: System, Local Address: Any, Remote Address: Any, Protocol: TCP, Local Port: 80, Remote Port: Any, Authorized Users: Any, Authorized Computers: Any, Authorized Local Principles: Any, Local User Owner: Any, Application Package: Any.

Furthermore, disabling both Windows Firewall and Windows Defender made no difference. I have not installed any other security or firewall systems. It appears that something is preventing port 80 requests from public ip addresses from reaching Windows 8.1 Update IIS. Yet the success on Windows 7 demonstrates that the gateway router is properly forwarding outside traffic to the assigned IP address.

What could be blocking the public ip port 80 requests to Windows 8.1 IIS, and how can I correct it?

Answer 1

Problem solved. It turned out the cause was Check Point VPN v98.60.202, from Check Point Software Technologies. I had installed this software to connect to a corporate client's internal network.

I suspected this was the cause because of how VPNs work, so I had previously closed the VPN software, but that didn't solve the problem. I actually needed to completely uninstall the Check Point VPN software and reboot the computer to remove the hooks it makes into the Operating System's TCP/IP stack. That allowed IP addresses outside of the host's subnet to again be served by IIS 8.5.