After a server recovery last night, a networking component required for secure ("https") deliveries was not functioning correctly. This caused the real-time leads routed to that server to have "Connection refused" errors. This server happened to be the one that performs asynchronous (delayed or retried) deliveries, so all of the https transactions for those leads also errored. The problem was fixed today (5/8) at approximately noon central time. Our apologies for the inconvenience; we have updated our process to ensure this component recovers correctly in the future.