GPS Navigation on Houston Freeways: Need Urgent Advice

Hello, this is a bit of a technical/apple support question too but it's highly related to Houston so bear with me.

I just got my first car (new driver) and used it today to go to a place around 13 miles from where I live. I have zero knowledge of Houston roads, so I relied on Apple maps on my Iphone. Unfortunately, as I got farther from where I live, location accuracy and speed got worse and worse, and when coming back, I got lost for like an hour or two due to the navigation app not showing where I was. (I tried google maps too). My cellular data, wifi and bluetooth was on and I'm on an At&t prepaid plan. I found my way back somehow (by memorizing which exits to take on a short period where navigation worked) and navigation started working magically as I got closer to where I live.

Questions: Do you lose network connection/location data on freeways? What can I do for this to not happen again? Will TomTom's or similar that are sold on Amazon work better? Any other advice you can give me? Thanks!