Master node has no flow rate

I have 4 nodes in graylog-server clusters , but master node has not flow rate straight,
what’s the loadblance policy?
and how can I decentralized flow rate to 4 nodes?

no load balance policy
all GL nodes work as a standalone/independent node with common config/management user interface. no message traffic between nodes.

so you have to solve the load balancing.
You can do it many ways, all depends on you.

So share you environment, and maybe someone give some hint.