The wi-fi keeps disconnecting for my games.

I have an iPhone 6s using IOS version 11.3.1. My wi-fi keeps disconnecting on my iPhone for my games. I can search Safari, or check my emails, but my games have wi-fi problems. My daughter also reports that she can only play her games by using up her data because her wi-fi also does not work for her games. If I check to see if my ISP is connected, their app says my internet is connected. (I do not have access to cellular data on my iPhone). By trying multiple steps I have discovered that when my game does not work appropriately, I go to settings>wi-fi. I tap on my wi-fi's name, and I turn the green button to white. In orther words I turn off my wi-fi for my iPhone only. Then I immediately turn it back on. And low and behold the game works appropriately immediately. The Apple Care wireless team says that if I can search the internet using Safari or if the ISP's app says my internet is connected, then it must be a app problem. However since it is happening with multiple games, and I can resolve the problem by turning off my wi-fi connection, and turning it back on again, then it has to go back to the wi-fi connection for my games. Why would my iPhone allow wi-fi for Safari and Mail but not for non-Apple game apps? Any suggestions or ideas? This is not on only one game. It happens across all the games I play. The game keeps telling me that I am not connected to their server. BTW, I quit the game when I am not playing it by swiping up. I also turn off my iPhone all the way every other day or maybe even more often.