Thank you for reaching out. One possible reason for this issue could be that the Windows 11 PC is not able to authenticate with the Synology NAS or the Windows 10 PC due to a network configuration issue. Here are some steps you can try to resolve the issue:
- Try accessing the Synology NAS using the IP address instead of the hostname. (can you open the Synology's webui from the Windows 11 pc?)
- Try creating a new user account on the Synology NAS and use those credentials to access the shared folders.
- Check the firewall settings on the Windows 11 PC and ensure that it is not blocking the connection to the Synology NAS.
- Make sure the shares are not SMB1 only, this protocol has been disabled by default in Windows 11