Cannot connect to a port from outside even if Windows Firewall is OFF

I'm getting a strange problem in my Windows 2008 R2 server running on a Hyper-V Virtual Machine. My application is listening to port 8002, which is well listed in command: netstat -na

Now I'm able to telnet to the same port (8002) from the same system, but I could not Telnet to this port from another system in the same VLAN. I'm able to Telnet port 135 of the server from another system, but not to this port (8002). I had turned off the Windows Firewall, enabled logging, allowed all traffic etc, but there was no sign of the connection from outside system.

Even I checked to Telnet to some other ports, and to my surporise, some of the connected but some didn't. Also, I run the same application in different system, it got connected from outside. Hence, I deduce that this is not the problem with the application. Please help.

EDIT: The system (both Windows 2008 r2 & Hyper-V) is a newly installed one.

RESOLVED: This issue is resolved, after we have found that, the antivirus client installed at the Hyper-V hypervisor (not the windows VM) is blocking the connection! Still don't know,why it is happening to this AV client only! Thanks to everyone!