Well, apparently there was a firmware update pushed this morning from Sling (someone was standing by the box when it updated)... I guess the IP address change on Sunday was Comcast updating its security that other people had problems with back in August... That initiated the firmware update which now appears to be compatible with the current network settings...
OK, that's what may have happened. It's working again now and I'm looking forward to some Thanksgiving football in Paris!
Subject closed (until the next problem...)