Peakboard Hub has an integrated MQTT server that you can use for communication between your Peakboard Boxes. Simply activate it under [Settings].
Attention: Make sure that the port on Peakboard Hub server is enabled. This is 1883 by default.
Once the MQTT server is enabled and the Peakboard Designer is connected to Peakboard Hub, you can easily share a variable with other Peakboard Boxes that will have the same value for that variable. If a Peakboard Box changes the value of a shared variable, it will change for all Peakboard Boxes.