Net connection issue with my iphone?

I have a broadband connection in my home with D Link Dir 816 Wi-Fi router. The problem i'm facing is that when i browse on my laptop with windows 10 i don't face any issue but when i use my iphone on the same network the internet connectivity drops after some time. Then after some more time ( typically after 30-45 minutes) it again has net connection on my iphone. I'm totally confused about this issue. I also have tried with different router of tp-link.

HI this is to protect your home broad band from outside users.