[  475.450387] Could not find device with ifindex 2000 in netnsfd 11
[  475.450537] Could not find netns with fd: 2000
[  475.450633] Cannot link a netdevsim to itself
[  475.450737] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).