[  485.077563] Could not find device with ifindex 2000 in netnsfd 11
[  485.077728] Could not find netns with fd: 2000
[  485.077820] Cannot link a netdevsim to itself
[  485.077937] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).