There’s a diner in SF I frequent. I usually sit 15 feet from the door, on a busy retail corridor, with Verizon premium network access. My iPhone XS reports two bars of LTE but there’s never enough throughout for DNS to resolve. Same at my dentist’s office. I hope to live in a post slow internet world one day, but that is still many years away.
(The XS does have an Intel modem, known to be inferior to the Qualcomm flagship of the era)