Can I use my smartphone as a WiFi network adapter?
I have asked similar question. I couldn't get access to PC connected via USB (USB Tethering) from PC connected via WiFi (Mobile HotSpot). Solution was add routing for USB Tethering net on second PC.



$ sudo ip route add 192.168.42.0/24 via 192.168.43.224 dev wlp5s0


Here 192.168.42.0/24 is USB Tethering net, 192.168.43.224 is IP of Mobile HotSpot, wlp5s0 is WiFi interface of PC (Linux). (In my question I had two Android devices, so maybe this step is optional, I haven't checked).

Second, you should flush all the chains in ip table on Android device, e.g through Android Terminal Emulator. Assumed that device is rooted:



$ su
# iptables -F