Poloniex just got attack Ddos from hacker in short time, don't worry about this issue.
I don't like polo customer support ,even worst that yobit support.
Bittrex soon will replace poloniex.
I think Poloniex still better than Bittrex about maintain their sever under Ddos, if you use Bittrex in long time, you will understand if Bittrex receive a huge user online or DDOS attack, they will close their exchange in 3-5 hours as Bitcoin Cash in past days.