[ 1226.362700][T11124] Could not find device with ifindex 2000 in netnsfd 11 [ 1226.363821][T11124] Could not find netns with fd: 2000 [ 1226.364779][T11124] Cannot link a netdevsim to itself [ 1226.365952][T11124] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).