I belive there is no way to tell whether the packets are for your pc or your phone unless it's a well known server that would make no sense using on your phone, like a game server or any other application server that can only be used by a pc(os). I managed to play World of Warcraft while tethering(mobile hotspot).
If you are sure that you recive internet otherwise on the phone if not tethering(good reception and your internet doesn't fail no matter what) then try other methods like use ovi suite instead of pc suite or bluetooth if availabe, joiku spot or mobile hotspot.