I want to backup over my cellular.

Okay, so what happens when you try? You should be able to manually backup to iCloud over cellular, however you cannot automatically backup over cellular with iCloud. That setup requires you to be connected to wi-fi and power for the automatic backup. What does iCloud back up? - Apple Support

Hi buddy,

According to this support article: How to back up your devices using iCloud or iTunes - Apple Support, you need Wifi even for a manual backup:

4. Tap Back Up Now. Stay connected to your Wi-Fi network until the process completes.

You can check the progress and confirm the backup completed. Go to Settings > [your name] > iCloud > iCloud Backup. Under Back Up Now, you'll see the date and time of your last backup.

GB

And good morning to you. I'll have to double-check, as I have tested manual backups in the past, and thought that I was able to do one via cellular. I'll get back to you on that, once I disconnect my wi-fi and test.

EDIT: I stand corrected. I turned off wi-fi, and when going to try a manual backup, it is grayed out, and the message states that you must be connected to a wi-fi network to start a backup. Thank you for forcing me to look at that again.

You can't back up to iCloud using cellular. You need Wifi. If you don't have a Wifi connection, then back your device up to iTunes on your computer.

Best of luck,

GB

Well, it wasn't something I knew off the top....just a little faerie jumping up and down in the back of my skull shaking her head with big eyes and mouth in a large "O"....

GB