[ 1227.101016][T11130] Could not find device with ifindex 2000 in netnsfd 11 [ 1227.101662][T11130] Could not find netns with fd: 2000 [ 1227.102223][T11130] Cannot link a netdevsim to itself [ 1227.102897][T11130] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).