[ 1090.874543][T10969] Could not find device with ifindex 2000 in netnsfd 11 [ 1090.875650][T10969] Could not find netns with fd: 2000 [ 1090.876427][T10969] Cannot link a netdevsim to itself [ 1090.877208][T10969] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).