I cannot open the SW mobile app unless I’m connected to wi-fi. I’m using an iPhone X. If I’m using cellular, the app states I lost connection and try again. The fact of the matter is I never lost connection; the app refuses to open. I’ve uninstalled and reinstalled the app numerous times. The only time the app opens properly is when my device is connected via wi-fi.
Hmmm, have you sent a note to the Southwest team? Most of us here are other customers like you and I don't recall seeing others reporting this specific issue on the discussion forums. Though if others do have the same issue hopefully they'll reply to this thread!
Assuming you're on wifi (given what you described) you could use the chat function to notify Southwest. Or you can click the "Contact Us" link at the bottom of the discussion forum pages.
Southwest customer | Home airport DCA | Community Chamption