[AT&T Samsung Galaxy S 4 Q&A, Help & Troubleshootin] talon010:
Hi guys. This started with me having unfix-able, horrible wifi at my house leading me to look for a good mobile data plan where I can just hotspot (or tether) 4g off my SGH-1337 Galaxy s4 onto my desktop.

I got this phone in America (April 2014) on AT&T and then moved back to Australia (Late 2014). I unlocked it successfully and legitimately and it has been fine ever since using the provider Optus.

I found a decent plan with lots of data then went to check if my hotspot worked only to find it doesn't work and after some research I found out AT&T do something to restrict it after being unlocked; which I find to be ridiculous, why do they do this? When I pressed turn on hotspot it would say in small text at the bottom of the screen "mobile data is not available or invalid sim".

I then found a solution using Titanium backup but needed to root my phone first. After figuring that out (took about 4 different applications) using TowelRoot, I got Titanium backup and I backed up and uninstalled these two apps that apparently are the ones that cause this restriction. They are "Tetheringautomation 1.0.1." and "TetheringProvision 4.06.70". After doing this, hotspot worked for a few seconds then it turns off and displays this new error message: "Unfortunately, Settings has stopped." with a box and a prompt to press okay.

I've tried enabling the hotspot through widgets and through ES File Explorer's Net Manager and the same thing still happens.

I've tried clearing the cache and starting in safe mode and both did the same thing (after clearing the cache it worked for 5 seconds then gave the error, after this first time it gave the error straight away after that.).

I then tried this solution: http://xdaforums.com/show....php?t=2791938 with the xposed's x tether. After installing it and restarting my phone, the hotspot worked for about 20 seconds, I found it on my computer and connected to it but google.com wouldn't load (so I guess it wasn't working properly) and then it dropped out and turned off. Now it is back to saying the same: "Unfortunately, Settings has stopped.".

I posted this elsewhere and was told to try the app fixes 'TrevE Mod for wifi tether' and 'Foxfi'. I tried both multiple times and still getting the same error message.

I tried another solution off the xda forums specific to my phone model and AT&T issue. It involved going to system/apps and renaming both tethering automation files then replacing them with a file that was provided in the post: http://xdaforums.com/show....php?t=2535141

After doing the whole process twice to make sure I did it right, It still didn't work, it gives me the first error message: "Mobile data is not available or invalid SIM" and I definitely have the 4g on and have double checked that it is working.

I have no idea what to do now, I've googled everything I can think of and read too many threads. I'm going to post this to multiple forums for coverage. Here on xda I will post here and in the General Q&A section too: http://xdaforums.com/general/help/issues-hotspot-tether-unlocking-att-t3181039

The build number is NC1. And I'm on 4.4.2. The hotspot worked fine when I was in America on AT&T. Tethering also gives me the same error message.

I am at wits end and have no idea what to do now. Please Please help me! I would be extremely grateful.

Thanks for even reading my issues, I really want this hotspot to work asap.