diff --git a/manila/share/drivers/service_instance.py b/manila/share/drivers/service_instance.py
index f17ad6e2c5..a845d1ab35 100644
--- a/manila/share/drivers/service_instance.py
+++ b/manila/share/drivers/service_instance.py
@@ -948,6 +948,8 @@ class NeutronNetworkHelper(BaseNetworkhelper):
                 device.route.clear_outdated_routes(subnet['cidr'])
             self._plug_interface_in_host(interface_name, device, port)
 
+    @utils.synchronized("service_instance_plug_interface_in_host",
+                        external=True)
     def _plug_interface_in_host(self, interface_name, device, port):
 
         self.vif_driver.plug(interface_name, port['id'], port['mac_address'])
@@ -966,8 +968,6 @@ class NeutronNetworkHelper(BaseNetworkhelper):
         # here we are checking for garbage devices from removed service port
         self._remove_outdated_interfaces(device)
 
-    @utils.synchronized(
-        "service_instance_remove_outdated_interfaces", external=True)
     def _remove_outdated_interfaces(self, device):
         """Finds and removes unused network device."""
         device_cidr_set = self._get_set_of_device_cidrs(device)
diff --git a/releasenotes/notes/generic-route-racing-adf92d212f1ab4de.yaml b/releasenotes/notes/generic-route-racing-adf92d212f1ab4de.yaml
new file mode 100644
index 0000000000..688e1cfb62
--- /dev/null
+++ b/releasenotes/notes/generic-route-racing-adf92d212f1ab4de.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - Fixed race-condition in generic driver while updating
+    network routes in host.