"Connection terminated" is a response error when the server you are trying to connect to rejects incoming connections. Other servers reply this error when you enter bad login data in the window you use to connect. Please check that the username and password you are using are correct and the modem is installed properly in the Device manager and there are no yellow exclamation marks next to the device. You can enter Device manager using Start > Run > devmgmt.msc and press enter.
Keep in mind that this error has nothing to do with your antivirus solution or any firewall that is installed onto your computer. Also make sure your have enough access to connect to the server before initiating a connection.
