When the target of an internal Network Load Balancer establishes a TCP connection to its own Network Load Balancer, the target can get routed to itself.

Network Load Balancers preserve the source IP, so both the source and destination of the arriving packet are the private IP address of the target. Then, the host operating system sees the packet as invalid and fails to send response traffic, which causes the connection to fail.

Note: This connection failure happens only when the source and the target are the same. As a result, the connection issues happen intermittently, depending on the number of targets available to the Network Load Balancer.

To correct this type of Network Load Balancer connection failure, use an IP