Error 10061 on remote winsock connection

First of all, I'm spanish and I'll do the best to make me understand... (thank you).

I'm trying to make a connection between two remote machines using winsock control.

I'm making the tests using two machines on the same LAN and ... it works fine, but when I try to stablish the connection using the public IP address of the 'server' machine (going out and coming back in to simulate remote connection) and I receive this error code (10061 Connection Refused). (I have redirected the router port 5000 to the 'server' machine and this is the one I'm using to make the connection).

Any ideas? I've heard that could be a problem of the 'structure' (you cannot connect two machines on the same LAN through the public IP adress using winsock control).

Thanks!