I have a Samsung Galaxy S4 that I want to install Android 5.1 on. AT&T released this as an OTA last year (https://www.att.com/devicehowto/tutorial.html#!/stepbystep/id/stepbystep_KM1143907?make=Samsung&model=GalaxyS4I337), but I whenever I check for updates it says nothing is available. The phone is currently running Android 4.4.
Could this be because I'm currently living abroad and accessing the internet via local Wi-Fi? Is there another way to get the update?