[ 1180.117644][T10966] Could not find device with ifindex 2000 in netnsfd 11 [ 1180.119130][T10966] Could not find netns with fd: 2000 [ 1180.120075][T10966] Cannot link a netdevsim to itself [ 1180.121118][T10966] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).