diff --git a/core/imageroot/var/lib/nethserver/cluster/actions/create-cluster/60wgboot b/core/imageroot/var/lib/nethserver/cluster/actions/create-cluster/60wgboot
index fd7feefe1..f9f998aa3 100755
--- a/core/imageroot/var/lib/nethserver/cluster/actions/create-cluster/60wgboot
+++ b/core/imageroot/var/lib/nethserver/cluster/actions/create-cluster/60wgboot
@@ -33,7 +33,7 @@ read -r network < <(jq -r '.network')
 # 0. Allow connections to the wireguard UDP port from
 #    the default firewall zone.
 # 1. Trust connections from the wireguard VPN
-firewall-cmd --permanent --new-service=ns-wireguard
+firewall-cmd --permanent --new-service=ns-wireguard || :
 firewall-cmd --permanent --add-service=ns-wireguard
 firewall-cmd --permanent --service=ns-wireguard --add-port=55820/udp
 firewall-cmd --permanent --zone=trusted --add-source="${network}"
diff --git a/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/00validate_cluster b/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/00validate_cluster
index feef492fa..df056f7ad 100755
--- a/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/00validate_cluster
+++ b/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/00validate_cluster
@@ -9,20 +9,21 @@ import json
 import sys
 import agent
 import agent.tasks
+import requests
 from aiohttp import ClientConnectorCertificateError, ClientResponseError
 
 request = json.load(sys.stdin)
-
+endpoint_url = request['url'].rstrip('/') + '/cluster-admin'
 rdb = agent.redis_connect()
-
 network = rdb.get('cluster/network')
 
 if network:
     agent.set_status('validation-failed')
-    json.dump([{'field':'url', 'parameter':'url','value': request['url'], 'error':'cluster_network_already_set'}], fp=sys.stdout)
+    json.dump([{'field':'url', 'parameter':'url','value': endpoint_url, 'error':'cluster_network_already_set'}], fp=sys.stdout)
     sys.exit(2)
 
 try:
+    requests.head(endpoint_url, verify=request['tls_verify'], timeout=8.0)
     validate_auth = agent.tasks.run(
         agent_id='cluster',
         action='list-actions',
@@ -32,15 +33,23 @@ try:
             "isNotificationHidden": True,
         },
         parent='', # Our AGENT_TASK_ID is useless in another cluster: force parent to empty string
-        endpoint=request['url'].strip('/') + '/cluster-admin',
+        endpoint=endpoint_url,
         tls_verify=request['tls_verify'],
         auth_token=request['jwt'],
+        retry_attempts=1,
     )
-except ClientConnectorCertificateError:
+except (requests.exceptions.SSLError, ClientConnectorCertificateError) as ex:
     agent.set_status('validation-failed')
+    print(agent.SD_ERR, ex, file=sys.stderr)
     json.dump([{'field':'tls_verify', 'parameter':'tls_verify','value': request['tls_verify'], 'error':'cluster_tls_verify_error'}], fp=sys.stdout)
     sys.exit(3)
-except ClientResponseError:
+except ClientResponseError as ex:
     agent.set_status('validation-failed')
+    print(agent.SD_ERR, ex, file=sys.stderr)
     json.dump([{'field':'jwt', 'parameter':'jwt','value': '***', 'error':'cluster_auth_error'}], fp=sys.stdout)
     sys.exit(4)
+except requests.ConnectionError as ex:
+    agent.set_status('validation-failed')
+    print(agent.SD_ERR, ex, file=sys.stderr)
+    json.dump([{'field':'url', 'parameter':'url','value': endpoint_url, 'error':'cluster_connection_error'}], fp=sys.stdout)
+    sys.exit(5)
diff --git a/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/50update b/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/50update
index 4a5118935..6c2d99fb1 100755
--- a/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/50update
+++ b/core/imageroot/var/lib/nethserver/cluster/actions/join-cluster/50update
@@ -25,6 +25,7 @@ import agent.tasks
 import hashlib
 import json
 import sys
+import socket
 
 # Action summary:
 # 1. Send the join request to the remote cluster leader
@@ -73,7 +74,9 @@ response = agent.tasks.run(
     progress_callback=agent.get_progress_callback(20,98),
     auth_token=jwt,
 )
-agent.assert_exp(response['exit_code'] == 0)
+if response['exit_code'] != 0:
+    print(agent.SD_ERR + "add_node error:", response["error"], file=sys.stderr)
+    sys.exit(2)
 
 node_id = response['output']['node_id']
 agent.assert_exp(node_id > 0)
@@ -82,6 +85,15 @@ print(f"Leader response is successful: the new node ID is node/{node_id}!", file
 
 join_node_data = response['output'] # add-node response is forwarded to join-node
 
+try:
+    # Resolve the leader endpoint address to an IP string:
+    peer_hostname, peer_port = join_node_data['leader_endpoint'].rsplit(':', 1)
+    socket.getaddrinfo(peer_hostname, peer_port, proto=socket.IPPROTO_UDP)[0][4][0]
+except Exception as ex:
+    print(agent.SD_ERR + "leader_endpoint error:", ex, "DATA", join_node_data, file=sys.stderr)
+    print(agent.SD_NOTICE + f"After the issue is solved, remove node {node_id} before running a new join attempt.", file=sys.stderr)
+    raise
+
 # Start the action that switches Redis to replica of the new leader.
 # join-node has to give us enough time to write our response back to the
 # UI caller.
diff --git a/core/ui/public/i18n/en/translation.json b/core/ui/public/i18n/en/translation.json
index 9cbe92338..0c68b0baa 100644
--- a/core/ui/public/i18n/en/translation.json
+++ b/core/ui/public/i18n/en/translation.json
@@ -202,6 +202,7 @@
         "the_join_code_cannot_be_parsed": "Join code cannot be parsed",
         "cluster_tls_verify_error": "TLS certificate of leader node is not valid",
         "cluster_auth_error": "Invalid response",
+        "cluster_connection_error": "Failed to connect to the leader node at address {value}",
         "redirect_cluster": "Worker Node",
         "redirect_cluster_description": "This node is a worker of the cluster now. Click the button below to access cluster administration page on the leader node.",
         "redirect_cluster_link": "Go to cluster administration",
diff --git a/core/ui/public/i18n/it/translation.json b/core/ui/public/i18n/it/translation.json
index 224c33fc1..2c2bcfbb0 100644
--- a/core/ui/public/i18n/it/translation.json
+++ b/core/ui/public/i18n/it/translation.json
@@ -995,6 +995,7 @@
         "not_a_valid_ipv4_network": "Indirizzo di rete IPv4 non valido",
         "the_join_code_is_not_correctly_encoded": "Il codice di join non ha il formato corretto",
         "cluster_auth_error": "Risposta non valida",
+        "cluster_connection_error": "Connessione al nodo leader all'indirizzo {value} fallita",
         "the_join_code_cannot_be_parsed": "Il codice di join non può essere interpretato",
         "cluster_tls_verify_error": "Il certificato TLS del nodo leader non è valido",
         "the_join_code_can_not_be_decoded": "Il codice di join non può essere decodificato"
diff --git a/core/ui/src/views/InitializeCluster.vue b/core/ui/src/views/InitializeCluster.vue
index 178e62b43..53f62eb21 100644
--- a/core/ui/src/views/InitializeCluster.vue
+++ b/core/ui/src/views/InitializeCluster.vue
@@ -1578,7 +1578,7 @@ export default {
     joinClusterValidationFailed(validationErrors) {
       console.error("validation failed", validationErrors);
       this.isJoiningCluster = false;
-      this.error.joinCode = this.$t("init." + validationErrors[0].error);
+      this.error.joinCode = this.$t("init." + validationErrors[0].error, { value: validationErrors[0].value });
       this.focusElement("joinCode");
     },
     async onFileUpload(files) {