Symptoms

When Web Apps Connect to K2 NLB Production from a Web-Clustered Environment, we are getting the below error message on instantiating a process, especially if the web app is using K2 LB vDNS. However, if the app is using the direct node address/dns, no issue at all.

"Send failed with error: An existing connection was forcibly closed by the remote host"
 

Diagnoses

Need to check the F5 configurations between the NLBs
 

Resolution 
 
Test the F5 configuration between the two NLBs.

After troubleshooting the issue, this is a F5 configuration issue, and as recommended by the Network Eng. team, auto-map and x-forwarding have to be enabled on the defined K2 ports in F5 side to pass the user IP and session information when hitting K2 servers