The underlying connection was closed: An unexpected error occurred on a send.

When doing Publish from Build server to Target server. We are seeing following error:

Web deployment task failed. (Could not complete the request to remote agent URL 'https://<HOSTNAME/IP>:8172/msdeploy.axd?site=<OURWEBSITE>'.)

This error indicates that you cannot connect to the server. Make sure the service URL is correct, firewall and network settings on this computer and on the server computer are configured properly, and the appropriate services have been started on the server.

Error details: Could not complete the request to remote agent URL 'https://<HOSTNAME/IP>:8172/msdeploy.axd?site=<OURWEBSITE>'.

The underlying connection was closed: An unexpected error occurred on a send.Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

An existing connection was forcibly closed by the remote host                   0              0              WEBSITENAME

We've been troubleshooting these since DAYS [Not hours] - We've read all following blogs/articles. Tried all possible solution. Bu with no luck:

We’ve tried few things like :

1. Disable Firewall/Antivirus, Allow Port 8172
2. Make sure Hostname/IP gets resolved
3. Server’s IP and Port number is reachable : Yes – We verified it using Telnet and it can connect to Port 8172  and also verified Firewall rules as well – All good!
4. Verified all Web deploy related services are fine or not – and they are fine – We tried to run Powershell script given by Microsoft in Reference Link #2 – But no luck
5. Verified username and password are fine – They are fine – Verified it using remote desktop with those credentials
6. Reinstalled MSDeploy on SBX – and It didn’t helped
7. No any log entry in MS Deploy IIS Log [HEAD/POST]
8. Tried with MSDeploy command : msdeploy.exe -verb:dump -source:iisapp="Default Web Site",computername=https://<HOSTNAME>:8172/msdeploy.axd?site=Default%20Web%20Site,username=<USERNAME>,password=<PASSWORD>,authType=basic  -verbose –whatif

9. Fired MS deploy command from my local – as given in earlier email and monitored packets on SBX server using TCPView and netstat command

10. Found that : TCP Packet gets sent on 8172 and status : SYNC_RCVD – and then it drops packet
11. As I understand this is how flow works:
     - Web Management Service listens on 8172
     - If request received it calls MsDeploy.axd
      Somehow, packet gets reached to Machine – But after that it should forward it to IIS – And in turn IIS will send it to MsDeploy – And looking at log files – Packet is being dropped at machine level

References:

1. http://stackoverflow.com/questions/12959501/web-deployment-task-failed-when-using-webdeploy-in-vs2012
2. http://stackoverflow.com/questions/12959501/web-deployment-task-failed-when-using-webdeploy-in-vs2012
3. http://www.iis.net/learn/publish/troubleshooting-web-deploy/troubleshooting-web-deploy-problems-with-visual-studio
4. http://stackoverflow.com/questions/5841370/cant-get-my-ec2-windows-server-2008-web-stack-instance-to-receive-publishings
5. http://stackoverflow.com/questions/11479927/visual-studio-2012-web-deploy-to-windows-server-2008-r2-with-iis-7-and-msdeploy
6. http://stackoverflow.com/questions/11479927/visual-studio-2012-web-deploy-to-windows-server-2008-r2-with-iis-7-and-msdeploy

Anything obvious -- We are missing?