[ 1217.802275][T11121] Could not find device with ifindex 2000 in netnsfd 11 [ 1217.803329][T11121] Could not find netns with fd: 2000 [ 1217.804258][T11121] Cannot link a netdevsim to itself [ 1217.805372][T11121] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).