Hello @juanjo mateoskrol ,
Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question
I understand you are encountering the below error while creating virtual desktop collection
Error : Could not identify the state of the virtual desktop. Ensure that the RD Virtualization Host server. Ensure that the RD Virtualization Host server (Name of the server) is available on the network and that the virtual desktop (xxxxxx) is shutdown.
Action Item:
Please make sure that your VM template is created as Generation 1:
Open Hyper-V Manager, click to select the VM on Virtual Machines list, then, on Summary section we can find the Generation information.
Besides, please check Event Viewer to confirm that if there is any network relate error or warning on your virtualization host.
Or, if possible, re-run sysprepe for the image and try to add again to confirm the result.
Please "Accept as Answer" and Upvote if any of the above helped to help others in the community looking for remediation for similar issues.