ES goes to red when node restarts

Elastic Stack Elasticsearch
4

index conf are as below

{
  "index_patterns": ["*"],
  "order": 1,
  "settings": {
"index.number_of_replicas": 1,
"index.number_of_shards": 3,
     "index.merge.scheduler.max_thread_count": 1,
     "index.refresh_interval": "30s",
     "index.translog.durability": "async",
     "index.translog.flush_threshold_size": "1g",
     "index.translog.sync_interval": "10s",
     "index.unassigned.node_left.delayed_timeout": "10m",
     "index.mapping.total_fields.limit": 3000
  }
}