diff --git a/scenarios/uni04delta-ipv6/config_download.yaml b/scenarios/uni04delta-ipv6/config_download.yaml
index c60825bf5..83decfa97 100644
--- a/scenarios/uni04delta-ipv6/config_download.yaml
+++ b/scenarios/uni04delta-ipv6/config_download.yaml
@@ -111,3 +111,4 @@ parameter_defaults:
     IronicNetwork: ironic
     IronicInspectorNetwork: ironic
   IronicCleaningDiskErase: metadata
+  IronicDefaultNetworkInterface: neutron
diff --git a/tests/roles/ironic_adoption/defaults/main.yaml b/tests/roles/ironic_adoption/defaults/main.yaml
index 79ecc3942..17c08f744 100644
--- a/tests/roles/ironic_adoption/defaults/main.yaml
+++ b/tests/roles/ironic_adoption/defaults/main.yaml
@@ -14,6 +14,13 @@ ironic_patch: |
       template:
         rpcTransport: oslo
         databaseInstance: openstack
+        customServiceConfig: |
+          [DEFAULT]
+          {% if ipv6_enabled | default(false) -%}
+          default_network_interface=neutron
+          {%- else -%}
+          default_network_interface=flat
+          {%- endif %}
         ironicAPI:
           replicas: 1
           override: