Load balancer for opendistro node masters

Hi
I’ve a cluster with 4 node master and 5 data/ingest nodes.
Trying using nginx to make a load balancer from my 4 master nodes but not works, because i use on elastichsearch nodes dn verifications.

Some can help, how use a lb + node dn verification?

Any idea how use balancer on the front of my master nodes with ou without nginx ?