[ 1081.126092][T11106] Could not find device with ifindex 2000 in netnsfd 11 [ 1081.127004][T11106] Could not find netns with fd: 2000 [ 1081.127644][T11106] Cannot link a netdevsim to itself [ 1081.128442][T11106] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).