Remote Desktop: logoff all sessions of a user

Use Terminal Services Manager (in Administrative Tools) to connect to the server and see which sessions are still used. You can reset and logoff existing sessions from there. Remember that just closing the terminal session window does not log the session off. There are times, also, when network hiccups will kick someone out of a session resulting in a dangling session. I've seen it frequently where a VPN user gets booted off the VPN connection while connected to a terminal session. This nearly always results in a dangling terminal session in my environment.

EDIT: If you don't have TS Manager installed, install the additional admin tools from AdminPak.msi which is located in \Windows\System32 on the server.

The RDP-TCP Listener "listens" for inbound RDP requests, then assigns them appropriate other port numbers. So someone would connect on port 3389 and then the client and server would negotiate another port to continue the conversation.

The reason it exists at all is that it lets you set properties that affect all users that connect through that listener. Keep in mind that you can also have multiple listeners if you had different NIC's with different needs (though I can't think of a scenario now).