Your cluster is up, is you execute to allow rellocation of al the shards probably the cluster state change to green. This "unassigned_shards" : 56 are probably the replicas.
cluster.routing.allocation.enable
Enable or disable allocation for specific kinds of shards:
-
all- (default) Allows shard allocation for all kinds of shards. -
primaries- Allows shard allocation only for primary shards. -
new_primaries- Allows shard allocation only for primary shards for new indices. -
none- No shard allocations of any kind are allowed for any indices.
if you execute that you receive the actual configuration
curl -X GET "localhost:9200/_cluster/settings?pretty"
Here where you have the tag "enable": "all" you have "primaries"
`{"persistent" : { "cluster" : {"routing" : {"rebalance" : {"enable" : "all"},`
About the connection error, all the nodes in your cluster have the same elasticsearch version? In the update process you are following the steps for rolling upgrades?