I had the same problem. What worked for me was simply setting the ethernet to en0.
You can check under About this mac -> System Report -> Ethernet Cards -> BSD name. If it says anything else than en0 it won't work.
The fix was relatively easy:
1. Install the proper drivers (see above)
2. go to Folder:
/Library/Preferences/SystemConfiguration
- this folder is hidden, so best use the "go to Folder" option
3. delete these two files:
Networkinterfaces.plist
preferences.plist
4. Restart the computer. The computer should now automatically set the ethernet to en0
(Special Case: For some reason, it showed two ethernet drivers on my computer. One was en0, the other was en1. I couldn't access the internet with the en0, but as soon as I enabled the en0 connection, the challenge code showed up. I then copied the code, switched back to the en1 connection, authorized it and now Omni 2 is running smoothly.
To change internet connections, go to System preferences -> Network. With the + and - keys, you can add an ethernet connection and it also displays if it's en0 or not.)