HTTP pipelining and AWS ELB

Question

When an HTTP client sends pipelined HTTP requests, how does the AWS ELB handle them?

Sends one to each server in the target group and return responses in the same order?

Sends all requests from the same incoming socket to the same server?

The only information I found is https://docs.aws.amazon.com/elasticloadbalancing/latest/userguide/how-elastic-load-balancing-works.html

Application Load Balancers and Classic Load Balancers support pipelined HTTP on front-end connections. They do not support pipelined HTTP on backend connections.

But I do not understand the meaning of that sentence.

Answer 1

It means that the front end connections (like requests from a web browser) can be pipelined. In other words a web browser can open a single TCP connection to the load balancer, and send multiple requests over that single TCP connection.

However on the backend, the load balancer will open a new TCP connection to the server(s) for each of those requests that it forwards to server(s).