Netgear Nighthawk AC1900

I recently purchased a Netgear Nighthawk AC1900 because I increased my internet speed. I'm supposed to be getting 80Mbps. The Century Link tech told me to purchase this router to help with internet speeds so I did. When I test out the speeds on my iPhone 7, it only goes up to 40 Mbps. The tech came back today to test it out and he tested on his Android at 65-75Mbps. I'm wondering what could be the problem that my iPhone is reading slower download speeds than the tech's android? Any ideas? Thank you.