What does it mean if the communication (COM) indicator is red and how to handle it?
It means communication between battery and inverter is faulty.

Following actions can be taken to fix this issue.
①Check whether the proper battery model is chosen.
②Check whether the communication wire is broken, and if so, please replace it.
③Check if the connection between the battery and the inverter is correct and well.
④Check if the CAN wire is connected to the proper RJ45 terminal.