[ 1088.804644][T10974] Could not find device with ifindex 2000 in netnsfd 11 [ 1088.805340][T10974] Could not find netns with fd: 2000 [ 1088.805902][T10974] Cannot link a netdevsim to itself [ 1088.806605][T10974] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).