[racket] internet connect through ip sharer

hello
there are two computer.
one is in here, and another is in other country.
both of two computer connected to internet by IP sharer.
I want to make program that connect both computer and send and receive data.
but my trying fails again and agian

my trying looks like this
one computer runs following code
#lang racket
(require racket/tcp)
(define listener (tcp-listen 80))
(define-values (in out) (tcp-accept listener))
(display "received")

and another computer runs following code
#lang racket
(define-values (in out) (tcp-connect "destiny ip" 80))
(print "string" out)

when I run the both of code in my comptuer with set the "destiny ip" as
"local host", it works. but it fails again and again when I try to connect
to other computer

your little aid would be very helpful for me
thanks in advanced

I've been sent similar question before but I still have no idea how to fix
it so I submit similar question again sorry.
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