I've had a Mobley in my RV for the last couple of years and don't have any problems with 2 hour time limit shutdown. But as I recall that was the default setting in the Mobley after some update that AT&T did a while back. To reset it to no time limit requires you to log into your Mobley as System Administrator and change the time limit to unlimited. The instruction booklet that came with my Mobley tells you how to log in as Admin and do this.
BTW, my Mobley has been powered up in my RV since my last camping trip and I just checked it - it's still up and running fine.