EV3 Wired Brick to Brick communication I'm currently working on a project for my intro to engineering class.

As it stands now, one brick is running a LabView program to intake data from a 'barcode' and another brick runs a  Matlab program that reads a marble with the color-sensor, and can pass or deny the marble.

I'm having an issue in making the bricks communicate with each other. Because there will be many other bricks in operation where this project will be tested, BlueTooth communication would be unreliable. 

From reading that I've done, there might be a way to perform hardwired communication by linking sensor port 4 of both bricks together, but I'm not sure of the specifics.

Both of the bricks are EV3, updated to the latest firmware.
The reading you have done about connecting input port 4 is for the NXT, not the EV3. The NXT has a special feature on that port for RS485 serial communications. This is not present on the EV3 bricks.

The EV3 bricks are designed to be able to be daisy chained via USB. There are "Message" blocks in the EV3 software for sending messages from brick to brick. I'm not sure about LabView and Matlab, but I suspect that have a similar block/function for sending messages.