iOS 7.1.2 Hotspot Issues

Ok, very simple:

I am trying to tether the Internet connection via the Personal Hotspot. The issue is the intermittent (but happens often) disconnects. I thought that it might be the Hotspot issue, but I am acctually not getting disconnected from the hotspot itself. Only every now and then, circa every few minutes, the internet connection disapears, and after 30 secons or so it appears again. How do I know it is a data connection issue? The disconnect happens both on the other iPhone that is connected to the hotspot, but also on my PC, regardless of whether it is connected via WiFi or the USB cable. During that outage, I cannot use the internet on my phone as well.

I run the iOS 7.1.2 on the iPhone 5s that was bought from the Apple store. My carrier supports the Personal Hotspot. I tried reseting the network settings and/or restarting the phone. Nothing helps. Please help.