The error (The remote server returned an error: (521). - Endpoint:) is down to Woo Commerce's server not responding when Mintsoft tried to import new orders, so it logged an error on the connect error page. Please check and see if all new orders have imported since the error was logged.
If orders have since imported fine, please do the following to mark the error as resolved:
Click Connect then Import Errors.
Tick the Error(s).
Select Resolve from the Bulk Actions.
Click Go.
If order has not imported since the error was logged, please raise a new case online and reference the title of this article with list of orders affected.