[US/Mexico border issue] Ever since switch to 5g, if my Dream 5g connects to a 1 bar cricket signal just south of the US border, my connectivity is screwed

Ok, so I’ve had Cricket service since 2019. This was never an issue, really - Never mattered what side of the border I was on. My older 4g phones would effortlessly switch back and forth between ATT Mexico and Cricket, depending on proximity to the Rio Grande. 

However, when I got Cricket Dream 5g phones (and thus 5g), our phones will sometimes insist on connecting to cricket in the US instead of ATT Mexico while riding around in Reynosa, where we spend most of our time. It’s like getting some kind of parasite! In Mexico, the US signal is obviously too weak to work, but no amount of rebooting/going in and out of airplane mode fixes this. On other phones, like my Samsungs, I could go into network settings and choose a provider. 

Are there any ideas on how this might be remedied? I worry more than anything about my wife sometimes when she’s in the downtown market near the border and her phone suddenly goes US mode. To even text me and let me know she’s ok, she has to walk to the international bridge, where the 5g signal is unmistakable.