[ 1227.690846][T11109] Could not find device with ifindex 2000 in netnsfd 11 [ 1227.691624][T11109] Could not find netns with fd: 2000 [ 1227.692160][T11109] Cannot link a netdevsim to itself [ 1227.693191][T11109] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).