Apple Remote Desktop (3.8.5) on multiple network interfaces

Situation:

Running Remote Desktop between an iMac and a Mac-mini, both running up-to-date El Capitan. ARD version 3.8.5

Both computers are on two networks, the WiFi network having the internet connection and is therefore "Primary" and a machine-to-machine link on wired ethernet. The WiFi and ethernet are on separate sub-networks.

In Yosimite, ARD 3.8.4, the Remote Desktop app on the Mini would announce (over Bonjour) as "Active" on both wireless and wired interfaces and, from the iMac, I could choose which I wished to use. Usually the hard-wired, gigabit, ethernet connection so as to reduce network activity on the WiFi.

After updating both machines to 10.11.2 and ARD 3.8.5, the Mini announces as "Active" only on the WiFi connection and as "Offline" on the wired connection and is Remote Desktop will not connect over the wired link. (no change with 10.11.3)

I have tried every combination of options I could think of to try and force ARD 3.8.5 on the Mini to announce as "Active" on the wired connection. Right down to starting with no network connection, at all, on either machine, with all sharing and remote management turned off, re-booting both systems and leaving the WiFi connection turned off. All to no avail.

Perversely, file sharing works just fine! It is just the Remote Desktop/Screen Sharing (yes, I tried that too, in all combinations) that will not announce or connect on the wired link.

When both networks are active, the Sharing Preferences on the Mini show the IP address for the Primary network (WiFi) as well as the name (Nimitz.local) of the computer. However, if the WiFi connection is not active there is no IP address displayed and the '.local' is missing from the computer's name. It shows up as just 'Nimitz' not 'Nimitz.local'.

I have gone through all of the /Library, ~/Library folders, looking for anything possibly connected to this issue. I've opened files, checked files, replaced files and removed files to no avail.

So my question is: How do I get Remote Desktop or Screen Sharing to connect over the wired interface? I would prefer not to try and go back to Yosemite and ARD 3.8.4 if at all possible.

Thank you for your patience!

Kyle