Moto G and APN Settings

I have had my Moto G 3rd gen for about a week now and I am using AT&T. I've had decent coverage and have been able to use LTE but I am using the default APN that the phone provides when adding a SIM card. I also notice that when I am not using LTE the phone drops back to 3G.

I have not found any information about the correct APNs for my carrier. Is HSPA+ supported for this phone on AT&T and are the default APNs the best setting to use?