[ 474.032802] Could not find device with ifindex 2000 in netnsfd 11 [ 474.032964] Could not find netns with fd: 2000 [ 474.033045] Cannot link a netdevsim to itself [ 474.033150] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).