[ 1226.390649][T11132] Could not find device with ifindex 2000 in netnsfd 11 [ 1226.391367][T11132] Could not find netns with fd: 2000 [ 1226.391907][T11132] Cannot link a netdevsim to itself [ 1226.392623][T11132] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).