This utility solved the AT&T hotspot problem on my unlocked 950 XL Windows Phone that results in the "It seems like you are trying to use data, but don't have a data package..." message.

There are multiple reports online with AT&T users having this issue with the 950 XL.  Be warned that this software is for advanced users and you can really mess things up if you don't know what you are doing!

The steps below are what fixed it for me:

1. Download the Interop Tools for Windows 10 Mobile and follow the instructions to get it installed: http://www.windowscentral.com/interop-tools-windows-10-mobile

2. Edit the registry settings as noted by user imbushuo Wang on the Windows Central forums here: http://forums.windowscentral.com/microsoft-lumia-950-xl/414723-mobile-hotspot-tethering-950xl.html

• Open Interop Tools for Windows 10 Mobile. Find it in Settings > Extras.
• Open registry editor and enter the following :
  Registry Hive: (select) HKEY_LOCAL_MACHINE
  Registry Type: (select) String
  Registry Key Path: System\ControlSet001\Services\icssvc\Settings
  Registry Value Name: EntitlementRequired
  Registry Value Data: 0
• Tap Write Data
• Type DedicatedConnections in Registry Value Name field
• Tap Read Data
• Clear out the Registry Value Data field (so it's empty)
• Tap Write Data
• Reboot your phone and try your Mobile Hotspot!

MiniTool Partition Wizard is a great free-for-personal-use hard disk partition utility for windows.  Delete, combine, format, and re-size partitions with this easy-to-use software.  More from the developers website is listed below:

"MiniTool Partition Wizard Home Edition is a free partition manager software designed by MiniTool Solution Ltd. Our partition manager supports 32/64 bit Windows Operating System including Windows XP, Vista, Windows 7 and Windows 8. Home users can perform complicated partition operations by using this powerful yet free partition manager to manage their hard disk. Functions include: Resizing partitions, Copying partitions, Create partition, Extend Partition, Split Partition, Delete partition, Format partition, Convert partition, Explore partition, Hide partition, Change drive letter, Set active partition, Partition Recovery.
MiniTool Partition Wizard Home Edition is designated for home user only, to use MiniTool Partition Wizard in a business environment, MiniTool Partition Wizard Professional Edition is required."

Images from http://www.partitionwizard.com/free-partition-manager.html

CDBurnerXP is a great no-hassle CD burning software that will help you create a variety of different discs.  Supporting Data, video DVD, Audio, ISO images, and more, this FREE software is a great way to simplify your burning process. 

Don't let the "XP" in the title fool you though.  This software has worked in every version of windows I've tried, and if anything, the "XP" may only refer to its older style interface. 

All in all, though the interface may remind you of the long past XP days, if you need an easy, reliable, and FREE CD burning package, CDBurnerXP might be just what you are looking for!

Sporting a huge library of FREE apps that run directly off your USB drive, Portable Apps are a great addition to any computer users arsenal.  The platform and apps are easy to install, and you can have all YOUR apps anywhere you go! Just pop in your USB drive and go!

The app library contains everything from web browsers and system utilities to games, office, and productivity apps.