HTC One M8 to Nikon

I am using Sprint HTC One M8 H/K version, factory software - never unlocked. I bought Nikon D5300 which has the WiFi feature which lets the users to connect with the smartphones to access photos and capture the shots (phone acts like viewfinder). The problem I have is as following:
1. When I want to connect to the camera, I simply switch on WiFi in camera and search WiFi networks in M8. I found Nikon in the list and connect to the network.
2. Everything is perfect. Mobile connected to the camera and I use the Nikon app to load photos/capture pics. 1 min, photos are loading and phone disconnects with the WiFi. I changed all possible settings under Wifi settings and advanced WiFi settings, but no luck. WiFi connection disconnected as there is no internet connection. If there are other known networks phone connects to that network and if there is no other network (even if the mobile data disabled) Wifi dropped and my phone will be in dumb mode.
3. I believe it is a basic feature to allow connecting the network I want maybe for internet or for file sharing purposes. I connected the camera with IPhone 6, works like a charm and no issues noted so far.

If anyone have a suggestion/solution please help me overcome this problem. If there is none, is there a way to contact HTC and ask them for a software update or something to fix this?

Thanks