How to change MAX_CONNECTIONS in http_server

Somehow I don’t manage to increase the max connections.
I assume that changing the number of workers does the job.
So I switched from:

:- http_server([port(8086)]).

To this for starting the http server:

:- http_server([workers(10),port(8086)]).

The source code of the http_server tells me that 10 is
still below the tcp_listen() backlog parameter which is 64.
But it still only serves 6 requests in parallel. The

overall execution time is 2.4 seconds:

How can I make it server all 10 requests in parallel? Is this
maybe a subtle timing and locking issue somewhere, or
maybe even a browser artefact?

I am using this server and this load page for testing:

demo7.p.log (3,2 KB)
package.html.log (3,6 KB)

Ok, my bad this is a limit by the client side already
mentioned in rfc 2616 – hypertext transfer protocol,
section 8 – connections. For Chrome browser it is 6.

Would maybe go away by supporting HTTP/2
protocoll on the server side. I am just reading:

Is the per-host connection limit raised with HTTP/2?

Here is the waterfall diagram for a HTTP/2 server,
the overall execution time is around 1.3 seconds.