WCF Connection could not be established because the target machine actively refused

I just implemented a simple WCF server using net.tcp.

First, I use 127.0.0.1both the server address and the client, which is able to connect the WCF service.

Everthing ok. But when I try to use the internal IP 192.x.x.x, I get an error:

No connection can be made because the target machine actively refused it

Any idea what might trigger this?

Best regards

PS: I disabled auth on WCF. Even turn off the firewall everything ... Doesn't work ...