[ 1080.707721][T10970] Could not find device with ifindex 2000 in netnsfd 11 [ 1080.708435][T10970] Could not find netns with fd: 2000 [ 1080.708993][T10970] Cannot link a netdevsim to itself [ 1080.709909][T10970] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).