I have a headless server to be able to switch locations without bringing my saves with me all the time. And quite often I find that I have been playing only on my local save without being connected to the server. I did some research and found out how my playing pattern is causing this.
If I play and my internet goes down, I get noticed with a warning, which is very good. If i minimize or the OS is pausing the factorio-process, the server drops me and I get noticed with a warning which is also very good. However, if I pause the game and get dropped (after some minutes), when I unpause again I am disconnected from the server, and the only notice is a faded text in the console saying "Server stopped communicating, cannot continue in game." (which I don't notice). Then I play for many hours thinking that I am still playing on the multiplayer server, while only playing local.
There really should be a huge blinking red light. The screen should shake and the game should be screaming a audible warning when this happens

Who wants it anyway ? If you are playing a multiplayer game and gets disconnected, I cannot imagine someone wanting to just be playing along locally. (OK, maybe someone, but it should be confirmed with a button saying "yes I want to continue locally"

Sorry for the rant, just looked forward to continue a game, and found out this had happened and the latest savegame is in a computer too far away

(Possibly also not a bug per se)
/Dag