Sometimes it is easier to just give a standard working example, rather than explain why a snippet isn't working. I'm guessing it's your while(1)...but I didn't try your code.

A working server:

#!/usr/bin/perl
use Net::hostent;
use IO::Socket::INET;
use IO::Select;

my $s = new IO::Select;

$IP   = '192.168.0.1';
$PORT = 15005;

my $server = new IO::Socket::INET(
    LocalAddr => $IP,
    LocalPort => $PORT,
    Proto     => 'tcp',
    Listen    => SOMAXCONN,
    ReuseAddr => 1
);


# Listen for multiple connections. 
$s->add($server);
$s->add(\*STDIN);
print ">> $0 accepting connections on $PORT\n";

while ( my @ready = $s->can_read() ) {
    foreach my $fh (@ready) {

# if($fh == \*STDIN){ $in_text = <>; 
#  foreach my $fh (@ready){ print "$in_ip >> $in_text";} 
 # } 


        if ( $fh == $server ) {
            my $new = $server->accept;
            $s->add($new);
            my $hostinfo = inet_ntoa( $new->peeraddr );

            # Show IP that just connected. 
            print "CONN >> $hostinfo\n";
        }
        else {

  #my $in_ip = inet_ntoa($fh->peeraddr);#error-prone 
  my $in_ip = $fh->peeraddr ? inet_ntoa( $fh->peeraddr ) : "unknown";
  my $in_text = scalar <$fh>;

  # If the client closes the connection,  
  #remove this socket, but 
  #keep the script running, waiting/serving  
  #other connections. 
            if ( $in_text ne "" ) { }
            else {
                $s->remove($fh);
                $fh->close;
                print "DISCONN >> $in_ip\n";
            }

            # Every time "TEXT\n" is sent, display this 
            print "$in_ip >> $in_text";
        }
    }
}

print "Program end.\n";

#What its meant to do:  Listen on a port 
#for connections, allow multiple 
#connections at once (hence the foreach() 
#forking), and when the client 
#quits, successfully closes the connection.
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