I have recently purchased two AL88 and one ALex, for starters, in the hope of converting my studio to CopperLan.
I had exactly the same issue on my MacPro!
After fresh installation, no Ethernet Interface visible in the Pop-Up chooser.
I wasted almost two days in finding the issue.
In my case, the "culprit" were the Access Virus TI drivers.
After deinstallation of the Access Virus TI Suite, the Ethernet interface suddenly became visible in the CopperLan Manager PopUp window.
I do not quiet understand how these drivers may have affected the ethernet port on my Mac...
How can it be possible to administer a complex setup where third-party MIDI drivers are constantly updated?
I am starting to regret to having jumped on the Copperlan bandwagon if after updating the drivers of my instruments I have to cringe whether my MIDI still works or not.
I am a musician, I am used to MIDI being Plug `n Play and not Plug `n Pray!