[ 1236.295668][T11288] Could not find device with ifindex 2000 in netnsfd 11 [ 1236.296425][T11288] Could not find netns with fd: 2000 [ 1236.297075][T11288] Cannot link a netdevsim to itself [ 1236.297812][T11288] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).