Perhaps Microsoft should work with OpenWRT to get the linux version of ntttcp incorporated and built for routers as a package. I use iperf2/iperf3 because it is provided by opkg.
root@router:~# opkg find ntttcp
root@router:~# opkg install ntttcp
Unknown package 'ntttcp'.
Collected errors:
* opkg_install_cmd: Cannot install package ntttcp.
root@router:~#