Cluster Events Ports

Hey everyone!
I’m trying to send a few Parameters via JSON Cluster to Unreal Engine 5.0.3.
I know that I also have to send the length of the string in binary to the Primary node but I’m wondering to which port I have to send this? The JSON part to 41003 and the length in binary to 41004? Or both to 41003?

To check this I tried to send a JSON string out of Unreal but I cant find/read the command. Does anybody know what port Unreal uses to emit cluster events from blueprint?

Thanks in advance!