[ 1090.352125][T10975] Could not find device with ifindex 2000 in netnsfd 11 [ 1090.352807][T10975] Could not find netns with fd: 2000 [ 1090.353355][T10975] Cannot link a netdevsim to itself [ 1090.354043][T10975] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).