usb tethering goes off

Surfing the net is fine, but when I try downloading games from Steam or Uplay, the download starts for like 5 seconds and stops and after which I lose internet access on the connected network. Ive been doing this with no issues since a few weeks back, and this problem only popped up in the past...

Hello! This is a very odd problem I'm facing after doing certain changes. I somehow messed up something in port forwarding on my router page and now my phone can no longer accept usb tethering to my desktop..every time I turn it on, it goes off and says "USB tethering error" on phone. I have...