diff --git a/environments/network-environment-v6.j2.yaml b/environments/network-environment-v6.j2.yaml
index df9bf604fc..6c29a60d65 100644
--- a/environments/network-environment-v6.j2.yaml
+++ b/environments/network-environment-v6.j2.yaml
@@ -32,7 +32,9 @@ parameter_defaults:
 {%- endfor %}
   # Customize the VLAN IDs to match the local environment
 {%- for network in networks if network.enabled|default(true) %}
+{%- if network.vlan is defined %}
   {{network.name}}NetworkVlanID: {{network.vlan}}
+{%- endif %}
 {%- endfor %}
   # Customize the IP ranges on each network to use for static IPs and VIPs
 {%- for network in networks if network.enabled|default(true) %}
diff --git a/environments/network-environment.j2.yaml b/environments/network-environment.j2.yaml
index 0a851ecaa5..fff6039970 100644
--- a/environments/network-environment.j2.yaml
+++ b/environments/network-environment.j2.yaml
@@ -27,7 +27,9 @@ parameter_defaults:
 {%- endfor %}
   # Customize the VLAN IDs to match the local environment
 {%- for network in networks if network.enabled|default(true) %}
+{%- if network.vlan is defined %}
   {{network.name}}NetworkVlanID: {{network.vlan}}
+{%- endif %}
 {%- endfor %}
 {%- for network in networks if network.enabled|default(true) %}
 {%- if network.name == 'External' %}