Game has been crashing for me lately

I have no idea why, but for the past 2 or 3 days I've ben in game and all of a sudden attempting to reconnect comes up. And its not like its a few mins and I reconnect, attempting to reconnect stays up for a while and when I exit the game and try to reconnect that way, my screen turns black for a couple seconds then a window comes up saying firewalls may be the reason for not being able to reconnect and you can either hit retry or cancel. Retry doesn't work so I hit cancel and the "reconnect to game" turns into "game has crashed". I don't understand, I've always been able to play league with no problems and I haven't touched and firewall settings so why is this happening all of a sudden?

P.S. It doesn't happen every game, just maybe one out of three games I play.