Is Wifi the only way to download software upgrades?
Your profile does not indicate you have an S4. The AT&T seems to want to do it over WiFi but the Verizon S4 requires a computer connected download and a special installer from what I've read. There probably is a place to download it manually, on your computer, but a lot depends on your version of the S4.
I downloaded the upgrade via WiFi with Verizon. I think the first couple of days it was available you had to connect to a computer using the Verizon update service, then they pushed them out to the devices. In the past I've used WiFi or 4g/3g with my Verizon devices depending on whether I was at home or not. I usually plug in the charger to make sure there's no battery issues when downloading the update.
Went over to Starbucks and, after signing onto their free wifi, I waited at least 1/2 hour before the download even started. Finally got it done. It took well over an hour. It was over 400mg. Finally got it done. The battery life did go down quite a bit. It's been sitting on the charger now, but, so far, I haven't noticed anything different and I wonder what the download was all about. Does anyone know?