[ 1089.438671][T10964] Could not find device with ifindex 2000 in netnsfd 11 [ 1089.439393][T10964] Could not find netns with fd: 2000 [ 1089.440016][T10964] Cannot link a netdevsim to itself [ 1089.440706][T10964] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).