I wes recently playing a blitz game versus someone: They had 18 seconds left and I had 4 minutes. I disconnected for 20seconds, reconnected and it said I had lost on time with 0 seconds left.

How does this work? I completely got cheated out of a victory there.

How did you disconnect and then reconnect?

While disconnecting the screen displays a receiving information spinning chessboard, that reads something along the lines of: "Reconnecting, please wait."

Then when you reconnect it should resume with the time you were gone deducted from the timer.

@OP: Unfortunately, lag compensation corrects up to only two seconds of lag.

So after roughly 30 seconds you will just lose?

@OP: Maybe. The server can help counteract simple lag, but it can't be expected to rectify disconnections of all lengths of time.

I am negatively affected, too, as I am unable to play Live Chess at all, because my Internet connection is so unreliably sporadic. I recognize that the fault is not with Chess.com, but with my Internet service provider.

whirlwind, could I ask you if you know whether or not it counts lag towards the timer, without showing you a change?

I had noticed my time sometimes going down on my opponents turn and I contributed this to lag. However may it be possible that the timer was attempting to compensate and failing to? Thus luling me into a false sense of security? 

I am just mildly confused as to if there is a limit of D/C time before auto loss, or if the timer proceeds. At this point the loss does not bother me, I just want to understand how the timer works and how lag(even if minimal) effects Live Chess.

@OP: Unfortunately, I am not a computer expert, so I am not qualified to explain the varied circumstances that arise in Live Chess and the technical reasons for them. Basically, if lag (defined as the amount of time that information needs to be sent from your computer to the Chess.com server, to your opponent, and back again) is less than two seconds overall, your clock will be compensated.

Actual disconnections are different. If your computer displays a message like "Attempting to reconnect...," you may not receive full time compensation.

After being disconnected for a certain length of time, the game will be declared abandoned. I'm not certain, but I think that length of time varies.

I believe it is 2 minutes after disconnecting for it to forfeit the game automatically such that the game info will say "game won/lost by abandonment" however if time runs out first you will win/lose on time. I cannot explain the discrepancy where 20 seconds translates to 4 mins magically burning off your clock though sorry :\