I logged into my Rendu and could not see a user name and pwd settings anywhere. So I imagine the Rendu expects to be found on the network.
I would contact either of the 2 listed below (both companies work together) and describe your setup and ask if a Rendu can work in your situation?
https://www.smallgreencomputer.com/ or
https://www.sonore.us/index.html (also contains FIND MY UNIT)
If you click on the second link you will see a menu option called FIND MY UNIT. When I click that link, the web site located my Rendu on my private network. The Rendu guys wrote the SonicOrbitor operating system that runs on the Rendu’s so they have hooks into everything, including possibly passing a file with user name and pwd that can be read from some software hook on the SonicOrbitor operating system. This software is amazingly reliable and robust. I just love this companies products, especially for my office environment.
You could also pose a question on the Sonore sponsored Computer Audiophile forum,
https://audiophilestyle.com/forums/forum/24-sonore-sponsored/