Internet sharing on iPhone 4S does not work

I have for some months had to restart my iPhone 4S, to be able to use it as a hotspot, and let other computers connect to the internet via my iPhone. Now the hotspot completely stopped working, and the only way to share the internet connection, is to connect the computer with the USB cable to the phone. This is getting a real pain in the a**... Have anybody experienced the same problem, and is there a solution for this problem?

The iPhone connects fine to wireless netowrks (well, some types it won't connect to, but it's the same on my macbook).