Nosleep doesn't help but something has changed since yesterday. Even "frozen" windows become alive and the client resychronizes with the server after a while after mashing skills/clicking to move somewhere. Feels like it takes the same time that it took before "you have been disconnected" popped up earlier. Did you change the time the client has to respond to the server after lags before closing the connection or something ?
//btw after almost 12hrs online today I had only one window disconnected, and like 3 times "almost disconnected" nosleep window - took its time to react but stayed alive in the end