Alright. From the code that you showed us, I see that you are trying to open multiple sockets listening on the same port. You can't do that even if you specify SO_REUSEPORT. Here is why

       ...
       For IP  only  one  socket  may  be
       bound  to  a  specific  local address/port pair. For TCP a
       bound  local  socket  endpoint  (address/port   pair)   is
       unavailable for some time after closing the socket, unless
       the SO_REUSEADDR flag is set. Note that carelessly setting
       SO_REUSEADDR might make TCP more unreliable unless PAWS is
       used (see tcp(4)); the delay is needed to handle old pack-
       ets still in the network.
       ...
[download]

He does not use IO::Socket, you are correct; however, he does show you how to implement a pre-forking server.
That is what I was referring to when I posted that link.

--perlplexer