Wifi access point with USB-OTG ethernet?
Some carriers disable 3G tethering in order to make more money, so if your carrier has installed software on your phone before hand to stop tethering the only way to make it work is to root your device and install an application that will allow you to do that.

The reason why it only connects is maybe because creating a hotspot to share files/resources over a LAN is allowed but to access the internet isn't. Right now, the FCC is forcing Verizon in particular to allow users to be able to share their phone's 3G internet.