fix

network.yaml

@@ -181,9 +181,11 @@
             net.ipv4.conf.{{br.name}}.rp_filter = 0
             net.ipv6.conf.{{br.name}}.accept_ra = 2
             {% endfor %}
+            {% if ppps is defined and ppps %}
             {% for ppp in ppps %}
             net.ipv6.conf.ppp{{ppp.id}}.accept_ra = 2
             {% endfor %}
+            {% endif %}
       - name: dhcpv6 directory
         file:
           name: '{{ansible_user_dir}}/nextgen-router/services/dhcpv6'