There are 65535 ports your PC can listen on. The only important thing is that the first PC listens on the same port the other PC is trying to connect ("Port" and "Remote Port" in the TCP VIs). Some of these are reserved (For example 1-1024 are reserved for the system, 80 is the http port, 3363 is used by LabVIEW). Select a port and see if it works (personally I use 6340). Make sure your computers can communicate with a ping command, and that the port is allowed in the firewall.
Another option for you would be to use Datasocket. That way you don't have to bother with managing the communication and conversion code. Just search for it on the site.
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