Can't update software help

Same problem am having

Can you go to Settings>About Phone>Software Information, take a screenshot and share it here?

This is all I could post I made a video showing the issues but can't post it here

It check for software updates but nothing come up for the update kept saying isn't available at this time try again

Basically still on Android 12 an 4.0 an the latest for this s21fe is android 15 a. 6.1.1

I know. Carrier locked phones like yours will not get the update outside of their network.

We'll need to find firmware with an XAA csc. I've never had an FE device so I'll look into it and get back to you about how we can go about helping you out. Have you used Odin before?

What You'll Need:
1. A Windows PC or Windows VM
2. Samsung Drivers installed on that machine.
3. Odin
4. The correct firmware files

INSTRUCTIONS:

1. Go to https://samfw.com
2. In the search box, type in SM-G990U and select it from the list that shows up.
3. Scroll down to the table that shows the available downloads. The one at the top is for ATT, click that since it is your CSC. On the page that opens, you'll have various options for downloading that file. Go ahead and select one and download. If you scroll down a bit on that page, you will see a section marked "How to flash....." and it will have a link to download Odin from there. Go ahead and download it too.

With both the Odin tool and your firmware downloaded, you're ready to move on.

Will go to a Cafe an try it an let u know how it works out for me