[ 1079.038227][T11103] Could not find device with ifindex 2000 in netnsfd 11 [ 1079.038966][T11103] Could not find netns with fd: 2000 [ 1079.039611][T11103] Cannot link a netdevsim to itself [ 1079.040434][T11103] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).