[ 1129.224977][T11104] Could not find device with ifindex 2000 in netnsfd 11 [ 1129.225773][T11104] Could not find netns with fd: 2000 [ 1129.226335][T11104] Cannot link a netdevsim to itself [ 1129.227357][T11104] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).