[   84.972291] Could not find device with ifindex 2000 in netnsfd 11
[   84.972445] Could not find netns with fd: 2000
[   84.972530] Cannot link a netdevsim to itself
[   84.972639] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).