It is your local server where USB Redirector is running. It can be presented by two icons:
USB Redirector accepts incoming connections from remote computers;
USB Redirector works in connecting remote USB devices mode ONLY!
USB Servers Statuses and Properties.
Each computer in the Window 1 or Window 2 has its own status and properties. Computers' statuses and properties depend on whether USB device is located in the Window of USB devices available for sharing or in the Window of USB devices available for connecting.
USB Server localhost Statuses (Window 1)
It is your local server where USB Redirector is running. It can be presented by two icons:
USB Redirector accepts incoming connections from remote computers;
USB Redirector works in connecting remote USB devices mode ONLY!
Your server localhost operation mode depends on network settings that you can change using menu Settings->Local Server.
If you do not want remote computers connect your shared USB devices, you can switch USB Redirector to the mode "to connect remote USB devices ONLY!" In this case you can keep on connecting shared USB devices from the remote computers, but from your computer shared USB devices will not be connected.
In the Window 3 you can find more detailed information about localhost Server operation mode.
In this window you can see:
operation mode of network connections receiving;
on what TCP port connections are accepted;
in what sharing mode your USB Redirector operates.
Statuses of remote computers connected to your computer (Window 1)
As it was mentioned before in Window 1 your local Server is presented. But in this window you can also see remote computers that are connected to your PC at the moment 
. They are going to connect your shared USB devices.
In the Window 3 you can see TCP port only! On this TCP port remote computer is connected. If remote computer disconnects it will disappear from the list of computers in the Window 1.
Statuses and Properties of USB Servers where you are connected (Window 2)
In the Window 2 you can see the list of USB Servers that were added to your configuration.
There are two kinds of icons:
icon means that the connection to the remote computer is successful;
icon means that the connection to the remote computer is failed.
Connection fails in the following cases:
when it is impossible to connect to the remote computer over local network or Internet;
if USB Redirector versions are different;
if you are trying to connect to the platform with other Operating System (32 bit <=> 64 bit).
In the Window 3 you can find more detailed information about chosen Server.
Here you can find the following information:
host name or IP address of remote computer;
TCP port;
Operating System version of the remote computer;
USB Device Connection mode.
You can allow USB Redirector to connect all available for connection USB devices automatically from the chosen Server. In the Window 4 you can find checkbox where you can tick off to connect all available USB devices automatically from this Server or take USB Server out from this mode.