Ok, Mediacom says the box is bad, but I want a second opinion. I have a 779x, and everything works ok except the VOD. It loads fine, pulls all the EPG, and everything is ok until you attempt to watch a program. It then pops up with a grey box stating "In order to start cable service for this device, please contact your cable provider." It then has the CableCard ID, Host ID, and Data, followed by UnitAddress, Card S/N, eCM MAC, and Host MAC. You can see the first couple of frames of the movie in the background, and that's it.
Provider is Mediacom, FW is 10.57. They've hit the box, and I've power-cycled it multiple times (hard and soft) with no change. My secondary DCT (SD-only) works fine with the VOD. All signal stats appear to be good, the line tap was replaced last week, diags show all green. All other functions (DVR, HD channels, etc) work fine.