I am getting the same problem too, except my time and date are current. Could it be cause I don't live in the states. It's weird, cause I was just playing.
I forgot to mention that I get this message too "We are sorry! Pirates of the Caribbean Online is temporarily closed for maintenance from 12AM PDT and will reopen at 4AM PDT. We apologize for the inconvenience and appreciate your patience!". I tried logging on again, this time I got "the site is closed for maintenance". The weird thing is I was just playing before this happened, and I didn't get the pop up saying we're closing for maintenance.
I'm going to wait till the time for this "maintenance" is over and try then. I think the game is just confused cause I'm in a different time zone,
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It worked, I was able to log on after the supposed maintenance was finished.