DOLS: "error syncronizing offline application" 20%

DOLS sync stops at 20% with, “error syncronizing offline application.” I’ve duplicated this on multiple platforms and multiple networks, with a specific user’s subsription to an application. The Sync process works to completion for the original sync and the 1st sync after, but any subsequent syncronizations error out at 20%. Port 1352 is open, and I can ping the server by its dns name. I need help. Thanks.