[ 495.930693] Could not find device with ifindex 2000 in netnsfd 11 [ 495.930812] Could not find netns with fd: 2000 [ 495.930878] Cannot link a netdevsim to itself [ 495.930988] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).