here is a discussion about the issue and a download link to version 2.2 but I have not tried it myself.
https://www.jamf.com/jamf-nation/discussions/25600/apple-configurator-2-5-no-longer-supports-apple-tv-3rd-gen
zyber
Thank you for that info Zyber, greatly appreciated. I had managed to solve the problem last night thankfully but I might try and download that v2.2 for future use.
My solution was that I found a Beta v2.3 online, I downloaded it but couldn't run it as macOS High Sierra doesn't allow the "install from unknown sources" anymore.
So to install from unknown sources, open Terminal and type the following command:
sudo spctl --master-disable
Terminal will ask you for your account password.
The info above I found in this link and it works...
https://discussions.apple.com/thread/8087751If you go to System Preferences > Security & Privacy you will now see that "Anywhere" is now selected for the Allow apps downloaded from section.
Now just go and run the Apple Config 2.3 Beta and it will allow you to install the new C2kWireless profile on the Apple TV 3.
When the profile install was just about to complete Stage 4, it did flag an error in Config 2, I just left it for a moment and then pressed the Stop button. It still worked and installed the new profile on the Apple TV 3.
Hope this helps others in the future.
SM