diff --git a/lib/neutron_plugins/services/l3 b/lib/neutron_plugins/services/l3
index 2e96284357..09c08e3280 100644
--- a/lib/neutron_plugins/services/l3
+++ b/lib/neutron_plugins/services/l3
@@ -88,8 +88,10 @@ SUBNETPOOL_PREFIX_V6=${SUBNETPOOL_PREFIX_V6:-2001:db8:8000::/48}
 SUBNETPOOL_SIZE_V4=${SUBNETPOOL_SIZE_V4:-24}
 SUBNETPOOL_SIZE_V6=${SUBNETPOOL_SIZE_V6:-64}
 
-default_route_dev=$(ip route | grep ^default | awk '{print $5}')
-die_if_not_set $LINENO default_route_dev "Failure retrieving default route device"
+default_v4_route_devs=$(ip -4 route | grep ^default | awk '{print $5}')
+die_if_not_set $LINENO default_v4_route_devs "Failure retrieving default IPv4 route devices"
+
+default_v6_route_devs=$(ip -6 route | grep ^default | awk '{print $5}')
 
 function _determine_config_l3 {
     local opts="--config-file $NEUTRON_CONF --config-file $Q_L3_CONF_FILE"
@@ -121,7 +123,9 @@ function _configure_neutron_l3_agent {
             _move_neutron_addresses_route "$PUBLIC_INTERFACE" "$OVS_PHYSICAL_BRIDGE" False False "inet6"
         fi
     else
-        sudo iptables -t nat -A POSTROUTING -o $default_route_dev -s $FLOATING_RANGE -j MASQUERADE
+        for d in $default_v4_route_devs; do
+            sudo iptables -t nat -A POSTROUTING -o $d -s $FLOATING_RANGE -j MASQUERADE
+        done
     fi
 }
 
@@ -371,11 +375,13 @@ function _neutron_configure_router_v6 {
 
     # This logic is specific to using the l3-agent for layer 3
     if is_service_enabled q-l3 || is_service_enabled neutron-l3; then
-        # Ensure IPv6 RAs are accepted on the interface with the default route.
+        # Ensure IPv6 RAs are accepted on interfaces with a default route.
         # This is needed for neutron-based devstack clouds to work in
         # IPv6-only clouds in the gate. Please do not remove this without
         # talking to folks in Infra.
-        sudo sysctl -w net.ipv6.conf.$default_route_dev.accept_ra=2
+        for d in $default_v6_route_devs; do
+            sudo sysctl -w net.ipv6.conf.$d.accept_ra=2
+        done
         # Ensure IPv6 forwarding is enabled on the host
         sudo sysctl -w net.ipv6.conf.all.forwarding=1
         # Configure and enable public bridge