Shutdown gateway socket: Transport endpoint is not connected

[ds10025]

Morning
I'm getting above error in the error log.
Could some help in explaining how and & why?
Below is the code that generate it.
I see:
    # Done writing.
    # $gateway->shutdown( 1 );
    shutdown( $gateway, 1 ) # IO::Socket::INET is broken in Perl 5.005?
        or return $self->log( 4, "Shutdown gateway socket: $!" );
Dan