Trouble receiving photos on iPhone 8+

My wife works inside a large store inside a mall. Depending, I think, on where she is in the building and on load on the towers nearby, she often can’t view photos sent to her in text messages. Her Verizon service switches between internet and LTE but sometimes neither lets her download pics (texts are OK). What’s most frustrating is you’d think she’d be able to view the pics when she leaves work and is in her car on the way home. Sometimes she can, sometimes she can’t.

i’m guessing that some setting(s) are changing on the phone and not automatically re-setting. This is all a little above our tech levels so we may just go the a genius bar, but I thought I’d see if anyone here coujd help. TIA