now what you do is, you set your computer as a staic computer with a ip, choose one thats higher than the normal dhcp ones, say like 192.168.1.120 and you would be fine so you dont get the message of theres an error someone else has the ip in your network, then you go to your router page and choose a port matching your program your using, and enable it for your ip, ex the 192.168.1.120
and you should be good
if you got more questions post em up