We are aware of an issue affecting some broadband users which is preventing them from connecting.
It appears to be a database issue with a RADIUS server that handles username/password authentication.
Engineers are working on the issue and are hoping to have it resolved ASAP. There is no ETR at present.
The is affecting products ADSL, FTTC, FTTP.
The issue is not affecting leased line customers FLL, Ethernet over FTTC customers, EoFTTC, EFM or MPLS services.
Swift Internet NOC 
UPDATE.
Currently waiting for an engineer to arrive at the Data Centre where the RADIUS server is located. In the meantime, engineers are working on bringing a backup RADIUS L2TP server online to restore service.
UPDATE 2
Although we have no further update from engineers as yet, we are now seeing that affected users are reconnecting OK, so if you were affected, please reboot your router to re-establish connection.
NOC and third party engineers in the Data Centre have now restored the Radius L2TP server which means customers should now be able to re-authenticate if needed. If you are still struggling to connect, then please reboot your device and try again.NOC engineers are also making progress with the backup server and are currently running tests to ensure it is now back up and running as a full resilient service.