The "StudioLive_Series_III_AVB_Networking_Guide_19102017.pdf" explains everything in detail. A perfect addition is the "StudioLive_Series_III_Stagebox_Mode_Addendum_06102017.pdf".

You need to think of control and audio as separate tasks. The Series III mixers have ports for "Control" and "Audio Network". If you connect your router to "Control" and use dynamic addresses, you can use UC Surface on any device. I can't say it better than the Stagebox Addendum:

"Control: This is the primary communication between your StudioLive Series III rackmount mixer and your computer, iPad, or Android device. When networked
to your StudioLive, any device running UC Surface controls the mixers’ functions.

Audio: An AVB network connection enables routing audio to and from the StudioLive Series III rackmount mixer’s audio inputs and outputs with a StudioLive Series III console mixer in stagebox mode".

It should be added that the new stageboxes and the personal mixer are based on AVB features. They do not work as autonomous devices.