diff --git a/meta/io.murano/Classes/resources/ExistingNeutronNetwork.yaml b/meta/io.murano/Classes/resources/ExistingNeutronNetwork.yaml
index 0a84a0e32..bd27d9e30 100644
--- a/meta/io.murano/Classes/resources/ExistingNeutronNetwork.yaml
+++ b/meta/io.murano/Classes/resources/ExistingNeutronNetwork.yaml
@@ -29,6 +29,7 @@ Workflow:
       - $._netExplorer: new(sys:NetworkExplorer)
       - $._networks: null
       - $._subnetworks: null
+      - $._ports: null
       - $._internalNetworkId: null
       - $._internalSubnetworkId: null
       - $._externalNetworkId: null
@@ -57,6 +58,23 @@ Workflow:
               $.id = $this.internalSubnetworkName) and
                 $.network_id = $this._internalNetworkId).first().id
 
+      - If: $.externalNetworkName = null and $._internalNetworkId != null
+        Then:
+          - $ports: $._netExplorer.listPorts()
+          - $routerCandidates: $ports.where(
+              $.network_id = $this._internalNetworkId and $.device_owner = 'network:router_interface').
+              select($.device_id)
+          - $networkCandidates: $ports.where(
+              $.device_id in $routerCandidates and $.network_id != $this._internalNetworkId).
+              select($.network_id)
+          - $externalNetwork: $._getNetworks().where(
+              $.get('router:external') = true and $.id in $networkCandidates).
+              firstOrDefault()
+          - If: $externalNetwork != null
+            Then:
+              - $.externalNetworkName: $externalNetwork.name
+              - $._externalNetworkId: $externalNetwork.id
+
       - If: $.externalNetworkName = null
         Then:
           $.externalNetworkName: $._getNetworks().where(
@@ -120,5 +138,3 @@ Workflow:
           netRef: $._internalNetworkId
           subnetRef: $._internalSubnetworkId
           floatingIpNeRef: $._externalNetworkId
-
-
diff --git a/murano/engine/system/net_explorer.py b/murano/engine/system/net_explorer.py
index 7a13678e4..1e85c485b 100644
--- a/murano/engine/system/net_explorer.py
+++ b/murano/engine/system/net_explorer.py
@@ -187,3 +187,8 @@ class NetworkExplorer(murano_object.MuranoObject):
     def listSubnetworks(self, _context):
         client = self._clients.get_neutron_client(_context)
         return client.list_subnets()['subnets']
+
+    # noinspection PyPep8Naming
+    def listPorts(self, _context):
+        client = self._clients.get_neutron_client(_context)
+        return client.list_ports()['ports']