When the game goes into the background either because of screensaver or because I've shifted to another app like Line for too long, it has to reload - no problem, I get that. But it often then claims I should check my Internet connection, and it will keep doing that until I close it completely and reload.
There is no Internet connection issue when this happens. I am on an iPad Air 2 with the latest iOS update. I have heard this is an issue for other players, too.
When I'm in a hurry to get back for, say, a mining reset or an attack, it's a real problem. Are you working on this?