You would need to call
t = tcpip(0.0.0.0,3000,'NetworkRole','server');
multiple times, once for each client.
Unfortunately there does not appear to be a timeout for the fopen() property of tcpip objects, and the fopen() is blocking, so you do not appear to be easily use the strategy of running a new tcpip/fopen with timeout after a successful fopen() in order to wait for potential new clients.
This suggests to me that the approach would have to be something along the lines of using parfeval() to create a future as the future can afford to sit around and wait while everything else goes on. I am not certain but this might limit the number of clients according to the size of your parpool.
To deal with communications between the future and the main work to be done, you might want to use parallel.pool.PollableDataQueue, using one in each direction for each future (each of them is unidirectional.)
I do not say that these are good ways to handle multiple clients, but keep in mind that MATLAB itself is single threaded.
... I suspect you might find it a lot smoother to use Java to create the sockets.
