MultiTX behavior on WR21

I have set up a MultiTX configuration on a WR21 serial port which always uses port 1600. I have tested it out on a computer whose address and port number matches one of the configured address for sending and it works correctly. In this case the computer that responds to the client (WR21) is sending from the port that the MultiTX data is configured to sent to for this computer (5001). When I try to send to the WR21 from a different computer (address that has also been configured in the serial port set up but with a port number of 8001) it fails to receive the packets. The only difference is that the second computer pick a random port to send from (not to). For example it is coming from 10.23.x.x port 57834 not the port 8001 that it received on. Both computers are sending to the correct port on the WR21 of 1600. Is this the normal behavior of the MultiTX configuration? Shouldn’t the WR21 accept packets from any port? By the way I have no firewall rules turned on.

MultiTX is for transmition of data from the serial port to multiple destinations over IP

connecting to the remote devices IP, Port selected at the same time