After a week of being sent around in circles I finally got this response from their support:

"Thank you for your patience with us. There is a known issue with our external pool connections that our developers are still working on. They are in connection with the developers of those external pools to find a way for the connection to work as before. This will be resolved shortly. Meantime, please point your workers to Mintsy Pools for better hashrates. Once we have connection with external pools we will inform you."