Establishing graphDB elasticsearch connector

I am trying to set up an Elastic search connector in graphDB with the following query:

PREFIX :<http://www.ontotext.com/connectors/elasticsearch#>
PREFIX inst:<http://www.ontotext.com/connectors/elasticsearch/instance#>
INSERT DATA {
    inst:field :createConnector '''
{
  "fields": [
    {
      "fieldName": "crop",
      "propertyChain": [
        "https://data.agrimetrics.co.uk/ontologies/general/isLocationFor"
      ],
      "indexed": true,
      "stored": true,
      "analyzed": true,
      "multivalued": true,
      "fielddata": false,
      "objectFields": []
    }
  ],
  "languages": [],
  "types": [
    "https://data.agrimetrics.co.uk/ontologies/general/Y1x5BN2XVZIvn1"
  ],
  "readonly": false,
  "detectFields": false,
  "importGraph": false,
  "elasticsearchNode": "http://20.67.27.121:9200",
  "elasticsearchClusterSniff": true,
  "manageIndex": true,
  "manageMapping": true,
  "bulkUpdateBatchSize": 5000,
  "bulkUpdateRequestSize": 5242880
}
''' .
}

I can see that the index is created in elastic:

[2021-07-29T08:45:10,252][INFO ][o.e.c.m.MetadataCreateIndexService] [richardElastic] [field] creating index, cause [api], templates [], shards [1]/[1]

but on the graphDB side I am getting a 500 error "Unable to check if index exists". This is the config of elastic:

{
  "name" : "richardElastic",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "skU191RwSnOu7FQiFB7dBg",
  "version" : {
    "number" : "7.13.4",
    "build_flavor" : "default",
    "build_type" : "tar",
    "build_hash" : "c5f60e894ca0c61cdbae4f5a686d9f08bcefc942",
    "build_date" : "2021-07-14T18:33:36.673943207Z",
    "build_snapshot" : false,
    "lucene_version" : "8.8.2",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}

and this is the YAML:

# ======================== Elasticsearch Configuration =========================
#
# NOTE: Elasticsearch comes with reasonable defaults for most settings.
#       Before you set out to tweak and tune the configuration, make sure you
#       understand what are you trying to accomplish and the consequences.
#
# The primary way of configuring a node is via this file. This template lists
# the most important settings you may want to configure for a production cluster.
#
# Please consult the documentation for further information on configuration options:
# https://www.elastic.co/guide/en/elasticsearch/reference/index.html
#
# ---------------------------------- Cluster -----------------------------------
#
# Use a descriptive name for your cluster:
#
#cluster.name: my-application
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
#node.name: node-1
#
# Add custom attributes to the node:
#
#node.attr.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
#path.data: /path/to/data
#
# Path to log files:
#
#path.logs: /path/to/logs
#
# ----------------------------------- Memory -----------------------------------
#
# Lock the memory on startup:
#
#bootstrap.memory_lock: true
#
# Make sure that the heap size is set to about half the memory available
# on the system and that the owner of the process is allowed to use this
# limit.
#
# Elasticsearch performs poorly when the system is swapping the memory.
#
# ---------------------------------- Network -----------------------------------
#
# By default Elasticsearch is only accessible on localhost. Set a different
# address here to expose this node on the network:
#
# network.host: _eth0_
# network.host: [_local_, _site_, _global_]
# network.host: 0.0.0.0
network.host: _eth0:ipv4_
cluster.initial_master_nodes: node-1
#
# By default Elasticsearch listens for HTTP traffic on the first free port it
# finds starting at 9200. Set a specific HTTP port here:
#
#http.port: 9200
#
# For more information, consult the network module documentation.
#
# --------------------------------- Discovery ----------------------------------
#
# Pass an initial list of hosts to perform discovery when this node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
#discovery.seed_hosts: ["host1", "host2"]
#
# Bootstrap the cluster using an initial set of master-eligible nodes:
#
#cluster.initial_master_nodes: ["node-1", "node-2"]
#
# For more information, consult the discovery and cluster formation module documentation.
#
# ---------------------------------- Various -----------------------------------
#
# Require explicit names when deleting indices:
#
#action.destructive_requires_name: true

Any help gratefully appreciated. This appears to be the relevant section of the logs:

[ERROR] 2021-09-02 13:06:15,723 [worker http://10.7.3.7:7080/repositories/farmData@http://10.7.3.5:8080/repositories/farmData | c.o.t.r.a.ClusterOperation] Error while executing transaction
file:/opt/graphdb-data/graphdb-master-home/data/repositories/farmData/txlog/transactions/d84/d84b8d2c-d410-49f5-a06a-a7cb18e390d8.tar
org.eclipse.rdf4j.http.server.HTTPException: null
    at com.ontotext.trree.util.Http.call(Http.java:50)
    at com.ontotext.trree.replicationcluster.RemoteWorkerRequest.postNext(RemoteWorkerRequest.java:342)
    at com.ontotext.trree.replicationcluster.WorkerThread$3.call(WorkerThread.java:541)
    at com.ontotext.trree.replicationcluster.WorkerThread$3.call(WorkerThread.java:524)
    at com.ontotext.trree.replicationcluster.WorkerThread.execute(WorkerThread.java:966)
    at com.ontotext.trree.replicationcluster.WorkerThread.run(WorkerThread.java:322)