App not loading content on WiFi
Firstly, check the performance of other devices on your same WiFi. Are you getting the intended speed on it? Might be an internet issue at its core.

Secondly, there might be other WiFi from your neighbors that "overlap" with your WiFi and causing the issue. Use an app like this and see which networks are the same channel. 

Depending on how overlap, just change the WiFi channel in your router and see if it does the trick or not.