Hello
The error means that the destination cannot be accessible. You should check name resolution, firewall settings, proxy settings, as it may limit the connection. Also ensure that you are running the latest version of the client.
If you know the ip address or hostname of the destination computer. you can enter it in "pc name" text box in Microsoft Remote Desktop. Or you can enter it in "ip address" this text box in Microsoft Remote Desktop. To check if ip address or hostname both doesn't work.
If this worked find before, I consider that you could download and install Microsoft Remote Desktop for Mac latest Version or older version on your MAC to avoid some know issue. Check if it could remote connect.
Also some information below may helpful to try:
1, Flush DNS information
Open CMD and type ipconfig /flushdns and press enter.
Wait to when it has been done!
Write down ipconfig /registerdns and press enter.
Wait 10-15 minutes and try again to connect not using the IP.
- Add a dot at the end of the FQDN address
For example instead of "computer.microsoft.com" use "computer.microsoft.com."
- If it is within the same domain, use the .local domain
Instead of "computer.microsoft.com" use "computer.local"
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