[ 1224.698855][T11127] Could not find device with ifindex 2000 in netnsfd 11 [ 1224.699672][T11127] Could not find netns with fd: 2000 [ 1224.700218][T11127] Cannot link a netdevsim to itself [ 1224.701003][T11127] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).