[  489.666495] Could not find device with ifindex 2000 in netnsfd 11
[  489.666707] Could not find netns with fd: 2000
[  489.666809] Cannot link a netdevsim to itself
[  489.666915] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).