Most brokers server is not reachable at the moment. I believe it a nationwide outage with Australian Brokers. IC Markets, Pepperstone and FP Markets not reachable as at 5:30PM Greenwich Mean Time (GMT).
Not only MT4, but also Metatrader 5 platforms. A word should always be enought for the wise remeber to always use a solid stop loss no matter how solid a strategy is.