Can Windows Admin Center connect to a remote server?

Of course you can do that! Please check the step-by-step guide below:

https://docs.microsoft.com/en-us/windows-server/manage/windows-admin-center/use/get-started

Make sure you have WinRM & PowerShell remoting enabled, these are disabled by default in Windows 10 and to enable them you type "Enable-PSRemoting" in the PowerShell console with admin privileges. You also need to allow TCP connections from outside of your subnet. Type "Set-NetFirewallRule -Name WINRM-HTTP-In-TCP -RemoteAddress Any" from the same PowerShell console with admin privileges.