Thanks for the follow-up, Brandon. There have been no changes on my end. The PAP2T has been purring along since 2/19. My network is simple: DIR-655 sitting behind a (non-router) cable modem. The PAP2T hangs off the DIR-655. I have no ports forwarded for the ATA, though per this morning's support ticket discussion, I will add the appropriate ports when I get home this eve and see what that does. Not sure why I would need the forwarding as things have been working fine until this point.

Thanks for the detailed explanation! Even if I only understand part of it, it's bound to help us zero in on the actual problem.