I often use the mobile app to access the training material during my commute. Along the route I go through a couple of short tunnels which causes me to lose connectivity for few minutes (2 to 3 minutes each). I have noticed that if I "solve" the puzzle during one of these interruptions, the app is unable to verify I have solved the puzzle as it times out on its attempt to synch with the server. Is there a way to allow the app to re-attempt a synch? Also, I have noticed that on another app (i.e. chess.com) it appears to hold a couple of puzzles in memory and so as not to encounter the same issue. Is it possible to do something similar with the Lichess app?