Welcome to the forum. Questions:
- Shouldn't the seed hosts be port 9300? You have 9200, but shouldn't put a port here unless it's unusual; port 9200 is for REST API operations, but the cluster internally works on the transport interface, usually port 9300 - remove your :9200 and I bet it'll be happy.
Minor things:
- Are you sure you are using the JVM 11, not the JVM bundled with V7?
- What does 'in public' mean on a firewall, as public & elasticsearch don't go well together, security wise.
- Why set network.publish_host as it'll use network.host?