Hello @pablo ballesteros
Welcome to Microsoft Q&A Platform.
The error 204 can be related to many different reasons, i would suggest checking the threads below that are related to the same topic:
https://learn.microsoft.com/en-us/answers/questions/187583/rdp-works-pc-to-pc-but-i-get-error-code-0x204-mac.html
https://social.technet.microsoft.com/Forums/en-US/941a9c4e-ed79-4347-8989-38fa8eeb29d8/error-code-0x204-remote-desktop-mac?forum=win10itpronetworking
https://learn.microsoft.com/en-us/answers/questions/362627/microsoft-rdp-error-code-0x204-in-macbook-pro-m1.html
I hope this helps!
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