I've had the exact same issue running for a month now where every Monday morning when I get to work our line is down (cannot authenticate) So every single time I called Telkom (their offices open at 7am btw), they re-create the port (never solves anything) and then open a "ticket". Come 2pm-3pm the line works again. After doing that 4 Mondays in a row they finally said it's an exchange issues, which they fixed the following day. Been working for 2 weeks now *holding thumbs*