I’d reboot. If the cable was out a while the interface could set itself down.
I could show you how to check and bring it up, but a reboot is faster.
Did it assign a new IP address to your device?
Either are possible.
Did Roon Server ever work for you on that machine? How long do you already own that machine / is it’s firmware current (less than a year old)?
If not, you may have to contact the manufacturer and ask for support/newer firmware to make that machine compatible (again) with the current Roon Server software.
As @Martin_Webster mentioned, if you’re still having issues, please complete the template. We’ll be notified if you reply.
As of right now, I show the core to be online so knowing the networking specifics of your setup will help us determine what should be next if the issues are still persisting!
I finally got it to connect today. I followed everything that was written here and swapped the cat 6 out 4 times. Today it connected. Thank you all for the input.