Galaxy S5 not updating Android system

[Thelonius]

Hi, newbie here.
I have a Samsung Galaxy S5 unlocked AT&T. Provider is Straighttalk. The Android system has not updated beyond ver. 5.0 (not even 5.0.1). Here are numbers that may help provide a solution.
Ver. 5.0
Baseband ver. G900AUCU4BOF2
Kernel ver. 3.4.0-4432708
Please tell me how to get the phone to update to the most recent version.
Thanks, thelonius

 

[bkdodger]

Welcome to the forum... Check out SamMobile site they post all firmwares for your phone models.. I'm thinking you might have to do it manually .. I'm not sure how further the S5 is updated ..

Note10+

 

[LoudRam]

We still have a working S5 for my autistic son. His is on 6.0.1 marshmallow but VZW and Samsung stopped supporting our phone a few years ago. We use it for his music now via WiFi.