I was having the same problem. Spent two days trying everything I could imagine to get those two units working via direct connect ethernet cable. I just read your post and will try it tomorrow. Thanks a lot for posting that.
In any case I thought that, apart from having lots of videos and the manual, presonus failed in providing usefull information on that. I have many different brands audio equipment and never had this kind of problem of interconnection that took me too long to solve. And I ain't no TI person.
Anyways... thanks for the post. Hope this work tomorrow.