Hello,
Your problem is that you can connect to the server normally from the Windows 10 client, but not from the Android client, right? May I Know your server working environment?
First, make sure that the user account you are using has Remote Desktop access permissions. Add the Android client user to the Remote Desktop Users group.
Additionally, ensure that there is network connectivity between the server and client. If using a VPN, make sure your Android device is properly connected to the VPN.
It is also necessary to check the server's security settings to ensure that no IP addresses are blocked or have restricted access.
I hope this helps.
Best regards