MetaTrader4 trading platform doesn’t allow EAs(expert advisers) and trailing stops to work when the platform itself is offline or closed.
It is because the information of the script and trailing stop orders are not sent to the trading server.
As in all EAs and trailing stops will be working only within your MT4 trading platform, and the trading servers wouldn’t know what kind of scripts(EAs) or trailing stop orders are set in the platform.
MT4 trading servers only register open positions and pending orders.
Thus, you need to have your MT4 running continuously in order to keep sending signals of orders to the trading servers.
cTrader has trailing stop registered in the server
Spotware, the developer of the ECN trading platform cTrader has made updates in 2016, and now the cTrader platform also register the information of trailing stop in the trading servers.
This means that even if your cTrader trading platform is closed or offline, your trailing stop orders will be working as you have setup before.