AT&T Prepaid, Can't Use Data Even With Data Plan

All was good for the day. Was able to access the internet via my phone. Then all of a sudden I was not able to. Still able make and receive calls and texts, but no internet. As they say on the "IT Crowd", "Have you tried turning it off and back on again?", to which I did. When the phone came back online, it displayed a notification saying to "Sign into the AT&T network", similar to the message that you would see when signing into some public Wifi access points. When I would open the notification, it would display a webpage that said

AT&T Free Msg: It looks like you want to use data but have none available. You may need to 
add a data package, refill to use pay-per-use data or change to a plan that supports data. 
To check your plan and manage your account, start at att.com/myprepaid. If you just made a 
payment for your monthly plan with data, power your device off and back on, then try again.

I knew that I had mobile data plan enabled because it was working hours before and that the website in said message, stated that I had used 6 GB for the month. After multiple restart attempts kept getting the same message and was unable to browse any websites, so I called customer service.

I'll spare majority of the details of the actual call. Customer service said that their system showed that my phone needed to be updated, to which I responded couldn't have been the case because I had updated the phones OS about a week earlier. She then suggested that I check to see if another update was available to which I had to tell her multiple times that the phone couldn't check for updates since it did not have internet service. insert eye roll here She had to message a SME about the issue for how to proceed. It was at this point it occured to me that she was reading from knowledge base, but was probably searching for the wrong terms and thus the correct knowledge document was not coming up.

Long story short, I found a knowledge document on AT&T website that provided the data settings that your phone should have depending on its connection type. Looking at what my phone already had and what was listed on the site for my LTE compatible phone, the settings were missing a couple of parameters. Thus I went into the data settings for my phone and added the endpoint settings that were listed on the site, powered off the phone for about 10 minutes, restarted the phone, and data started working normally. Those mobile internet settings can be found on att.com.

No thanks to the customer representative, I figured out the issue myself and was able to the internet working again after updating the APN settings that were listed on the website. For those that are reading the AT&T forums, the responses provided there did not offer an answer. From reading the AT&T forums, apparently internet traffic, and probably other services, are routed differently through the network (presumably because they are billed differently) and often times prepaid customers get the short end of the stick and have more issues with AT&T's service.