On my S6, I used to be able to swipe down and turn the mobile data connection on or off with one touch. The new S8 doesn't seem to have that button available. Is there a way to restore it?
Pull notifications down. Pull them down again. Tap the pencil (to edit the icons). Look in there for the data toggle icon. (Samsung is known for removing it now and then.) You can add it back if it's not there but
a) the phone has to be rooted
and
b) you have to understand SQL.
The icons you see are in a database file, so you have to be able to find the record with the buttons, then add the data button.
i assume ur s8 runs oreo, pull down the quick settings panel, in the right most upper corner you'll see 3 dots next to the settings button, tap the three dots to view the button order & button grid options , tap button order, you'll be able drag the data toggle in place again, hopefully this works for you, cheers ( i see no reason to root unless i didn't get ur issue right )