[  469.177303] Could not find device with ifindex 2000 in netnsfd 11
[  469.177441] Could not find netns with fd: 2000
[  469.177505] Cannot link a netdevsim to itself
[  469.177584] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).