MR816csx and VST System Link problem

Hey folks,
I am trying to get my MR816csx to work with VST System Link but so far to no avail.
Followed the instructions to hook up Optical in to Out to test if System Link will work but so far no luck.
Does anyone know if this Steinberg device even supports System link? I´d be damn surprised if it didn´t being from Steinberg and with all those nice I/Os. The MR Tools are confusing the hell out of me and I am truly not sure what I´m doing here.

Cheers for any ideas, hints or links to any tutorials.
Thx! Mark

SW Cubase Artist 9.5 (on other machine Cubase Pro 9.5)
OSX 10.13 on both machines
HW MacMini 16Gbyte Ram, SSD, Firewire Connector
Other machine: MacPro 3,1 with optical I/O

No answer so far and I was not successful getting this to work, although SPDIF of the MR816csx (self-connected) tested positively for VST System Link. However, I found another very interesting option to Sync up two instances of Cubase 9.5 with two macs regardless of the audio interfaces used, that I can now highly recommend after getting it to work, although it is not free of charge. The answer is: Dante by Audinate. I installed an instance of Dante Via on an external Mac Laptop running OSX 10.13 and hooked it up to a gigabit ethernet switch, connected to both Macs with Cubase 9.5. Both on which I installed Dante Virtual Sound Card. Then I connected them via the Dante Controller, a signal flow matrix application and tried VST System Link again. WOW! Success at last. Blue and Orange beacons, Computer Names show up and off we are - perfect sync. If there are other users interested in this or can share their experiences, feel free to reach out! Mark

hi there.
can u use it to play virtual instruments from second computer ?
let say you have main machine with cubase installed, and a second machine installed with some VSTI and vst system link (if its still works and dowloadable)
can you play/use those VSTI from second machine via midi and audio from the main machine ?
if yes what do i need ?
1: vst system link
2: dante via software
thanks !