Hello @Pedro_Conde,
Thanks for your report, to start, may I kindly ask that you provide a bit more information on your current setup using this link as a guide?
Furthermore, can you please let me know on which Audio Zone you are having this Transport error? Can you also please confirm that you have tried rebooting your Core machine and all relevant networking hardware that Roon uses to communicate?
Please let me know when possible.
Thanks,
Noris