You will be playing a server (at least the official servers) and you will get disconnected due to the server timing out. When this happens the server will not appear on your list when you try to rejoin it. Im not sure that you will always lose vision of a server after being disconnected via timeout, but it seems whenever i lose sight of one that its after a timeout error.
Perhaps this is just me, but i have heard of other people dealing with the same type of thing.
just trying to be productive here.
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