Dexcom G5 App Lost Signal Question

Hello everyone. My 10 year old son was diagnosed T1 a few months back. We got him the Dexcom G5 about 3 months ago. The Dexcom is absolutely amazing. It makes living with diabetes so much better than it was for my cousin and uncle who I've watched live with T1 most my life.

Anyway, there is one annoying issue I'm wondering if anyone has an answer for. My son had my wife's old IPhone 5 and we used it for the Dexcom app. However, whenever he would watch YouTube, Netflix, or Hulu, the Dexcom would lose signal. I looked online, but could not find an answer as to why. I called Dexcom and they basically said it could be the lack of memory on the old phone. That it couldn't run both apps with the memory it had and consequently prioritized the video app over the Dexcom app. Ok. That seems logical. It is an old phone my wife once dropped in the pool. We debated getting him a new phone, but the the occasional lost signal wasn't that big of a deal.

Then a couple days ago, that old phone died. We went to Verizon and got him an IPhone 7 with 128g memory. We thought, "good, now we won't have to deal with the lost signal issue anymore." No such luck though. We now have the same issue.

Does anyone have an answer both as to why this is happening and what can be done about it? We can't be the only ones dealing with this, but I can't find anything online about others dealing with this.