Can you link an instruction manual for the Innuous mini mk3 device? I’m not familiar with it. 
 

Unless it is an NAS, it won’t connect either wirelessly, or with an Ethernet cable. If it is a player of some sort, the analog out port on it should be connected with RCA cables to the line in port on the Sonos, and the normal line in instructions should be followed. 

On https://innuos.com/kb/connecting-network-streamers/ I see instructions for a UPnP set up. If you cannot add de Mk3 in the usual way (by providing a link to a server in the Sonos app), maybe this would work. I have no experience with either UPnP on Sonos or Innuos though…..

This service actually has a Sonos mode: Connecting to a SONOS System – Innuos – High-Fidelity Digital Music Servers and Streamers

Thanks for all the responses.  Controlav- i have been following the instructions on the Innuous site but the Port and Innuous are not finding each other.  “If it doesnt find a sonos network, make sure the devices… are active and on the same network so they can see each other”.  

Does this mean that I have to run them both back to my internet router (currently only the Innuous is and I only have 1 port available at this location),that they might communicate via wifi (both are on my wifi) or that I could connect them directly?  

thanks again.
 

So long as they are on the same subnet, and your router isn’t doing something insane, that is enough.

OK, what’s a subnet?

https://en.wikipedia.org/wiki/Subnetwork