diff --git a/gns3server/configs/iou_l2_base_startup-config.txt b/gns3server/configs/iou_l2_base_startup-config.txt
index 501355f6..4a09db82 100644
--- a/gns3server/configs/iou_l2_base_startup-config.txt
+++ b/gns3server/configs/iou_l2_base_startup-config.txt
@@ -13,7 +13,8 @@ logging console discriminator EXCESS
 !
 no ip icmp rate-limit unreachable
 !
-ip cef
+! due to some bugs with IOU, try to change the following line to 'ip cef' if your routing does not work
+no ip cef
 no ip domain-lookup
 !
 !
diff --git a/gns3server/configs/iou_l3_base_startup-config.txt b/gns3server/configs/iou_l3_base_startup-config.txt
index 81d574ff..67628f77 100644
--- a/gns3server/configs/iou_l3_base_startup-config.txt
+++ b/gns3server/configs/iou_l3_base_startup-config.txt
@@ -12,7 +12,8 @@ no ip icmp rate-limit unreachable
 !         
 !
 !
-ip cef
+! due to some bugs with IOU, try to change the following line to 'ip cef' if your routing does not work
+no ip cef
 no ip domain-lookup
 !
 !