diff --git a/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py b/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
index c73cd3df3b3..b7270039722 100644
--- a/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
+++ b/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
@@ -1492,17 +1492,19 @@ class OVNClient(object):
             'device_owner')
         if is_gw_port and ovn_conf.is_ovn_emit_need_to_frag_enabled():
             try:
-                network_ids = set([port['network_id'] for port in
-                    self._get_router_ports(admin_context, port['device_id'])])
+                router_ports = self._get_router_ports(admin_context,
+                                                      port['device_id'])
+            except l3_exc.RouterNotFound:
+                # Don't add any mtu info if the router no longer exists
+                LOG.debug("Router %s not found", port['device_id'])
+            else:
+                network_ids = {port['network_id'] for port in router_ports}
                 for net in self._plugin.get_networks(admin_context,
                                             filters={'id': network_ids}):
                     if net['mtu'] > network['mtu']:
                         options[ovn_const.OVN_ROUTER_PORT_GW_MTU_OPTION] = str(
                                 network['mtu'])
                         break
-            except l3_exc.RouterNotFound:
-                # Don't add any mtu info if the router no longer exists
-                pass
         return options
 
     def _create_lrouter_port(self, context, router, port, txn=None):
diff --git a/neutron/tests/unit/services/ovn_l3/test_plugin.py b/neutron/tests/unit/services/ovn_l3/test_plugin.py
index c4c12f081dd..448a5219dd4 100644
--- a/neutron/tests/unit/services/ovn_l3/test_plugin.py
+++ b/neutron/tests/unit/services/ovn_l3/test_plugin.py
@@ -1634,7 +1634,7 @@ class TestOVNL3RouterPlugin(test_mech_driver.Ml2PluginV2TestCase):
                 'network_id': 'priv-net'}
         ari.return_value = self.fake_router_interface_info
         # If we remove the router halfway the return value of
-        # _get_routers_ports will be []
+        # _get_routers_ports will be RouterNotFound
         grps.side_effect = l3_exc.RouterNotFound(router_id=router_id)
         self.get_router.return_value = self.fake_router_with_ext_gw
         network_attrs = {'id': 'prov-net', 'mtu': 1200}