Please consider implementing error messages that are more accurate/useful.
e.g.
Instead of “Check Internet Connection” at the MPQ loading screen, write “Servers Down at the Moment. Please Check Back in a While” if it’s a server-side issue. It saves the players hassle of checking their 3G connection or restarting routers unnecessarily.
I won’t defend D3’s ludicrous series of outages, but as someone who does work (in a totally different arena) with stuff requiring connectivity, I’ll note that it’s probably impossible for the app to tell the difference between a server-side or client-side internet connectivity issue if it can’t get to the server. Maybe a more generic message noting both possibilities would work instead.
Check if the user device has an IP address, or is on 3G. If yes, display “Server is down and we have no clue when it’s coming back”. If no, “Check your internet connection dummy”.