using supplied 01-netcfg.yaml as example

note the use of yes in place of true for dhcp4

roles/network/templates/network/netplan.j2

@@ -6,8 +6,8 @@ network:
   renderer: networkd
 {% endif %}
   ethernets:
-{% if wan_ip != "dhcp" %}
     {{ iiab_wan_iface }}:
+{% if wan_ip != "dhcp" %}
       addresses:
       - {{ wan_ip }}/{{ wan_cidr }}
       gateway4: {{ wan_gateway }}
@@ -16,12 +16,8 @@ network:
         - {{ wan_nameserver }}
       search:
       - {{ iiab_domain }}
-            optional: true
 {% else %}
-        {{ iiab_wan_iface }}:
-            addresses: []
-            dhcp4: true
-            optional: true
+      dhcp4: yes
 {% endif %}
 #{% if iiab_lan_iface == "br0" %}
 #    bridges: