[  492.314404] Could not find device with ifindex 2000 in netnsfd 11
[  492.314525] Could not find netns with fd: 2000
[  492.314593] Cannot link a netdevsim to itself
[  492.314672] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).