[Networking] class101:
Basically you need to be

1) connect the usb cable to the computer

2) Use the script in android su -c 'sh /sdcard/rndis.sh' (requires root and a terminal like terminal emulator, this will set the RNDIS network card to an ip in the 192.168.137.0/24 network, 192.168.137.1 as a gateway

3) On the computer side you right click your network card (not the RNDIS one but the ethernet one where the internet is coming from), and in the properties you enable 'Connection sharing'

Step 3) should share the internet connection from your internet card to the rndis card, And most importantly Windows will automatically assign to the rndis card the ip 192.168.137.1 (the gateway the Nexus will send to any internet request)

From there you should have the internet access to the mobile, like Google chrome, speedtest.net will work but most Android App will not detect the Internet because they are set to detect it through Wifi, the trick to workaround that is to connect to your Wifi box but assign an ip in the Range 192.168.137.0/24 and most importantly the wifi as to be set on the gateway 192.168.137.1 like that

wlan.sh

echo -- wlan0: flushing interface --
ip addr flush dev wlan0
echo -- wlan0: setting ip --
ip addr add 192.168.137.102/24 dev wlan0
echo -- wlan0: setting properties --
setprop net.dns1 8.8.8.8
setprop net.dns2 8.8.4.4
setprop net.wlan0.dns1 8.8.8.8
setprop net.wlan0.dns2 8.8.4.4
setprop net.wlan0.gw 192.168.137.1
setprop net.wlan0.gateway 192.168.137.1
setprop wlan.driver.status ok
setprop sys.sysctl.tcp_def_init_rwnd 60
echo -- wlan0: starting the interface --
ip link set wlan0 up
echo -- wlan0: setting route --
#ip route add default via 192.168.137.1 dev wlan0
busybox route add -net 0.0.0.0 netmask 0.0.0.0 gw 192.168.137.1 dev wlan0

wlanoff.sh

echo -- wlan0: stopping the interface --
ip link set wlan0 down
echo -- wlan0: flushing interface --
ip addr flush dev wlan0

to resume here to get full internet access as fast my computer goes, this is what I'm doing

- Plug usb cable in

- running su -c 'sh /sdcard/rndis.sh'

- enabling connection sharing in Windows (just the checkbox on the internet card, sharing tab)

- Enabling the Wifi on the Nexus (manually set to static in 137.0 network 137.1 gateway)

- I execute once su -c 'sh /sdcard/wlanoff.sh' && su -c 'sh /sdcard/wlan.sh' (to be sure the route is set correctly because when enabling Wifi on static, the gateway route doesn't show up in the route table when you do busybox route -n, the script should set the route correctly)

tip: Might be boring to write the su -c commands each time, here instead I add aliases to /etc/mkshrc file, reboot, now "rn" starts my interface and "rnoff" disables it =) (might need mount -o remount, RW /system to update that file)

In case you wonder why I'm doing all that this is because I'm far from my internet box and anything requiring a stable connection on a simple wifi is loosing connection and it is 30% of the speed of my internet box, after that, I get 100% of the speed and a stable connection and internet access to all the apps, no exceptions because my computer is not on Wifi but using cpl (internet over electricity, close to as fast as ethernet cables). So much better and no need of any third party tool to reverse tether.