I get 400 Mbps down standing at the door of that same diner. My understanding is that 4G bands are repurposed for 5G in rough proportion to the usage of 4G vs 5G devices at that tower, plus there’s some way to use a band for both. In any case I was having these indoor performance issues back in 2019. I’m pretty sure it’s an Intel issue, and any Qualcomm modem would be fine.