Server’s Internet Link is being Hammered

For the last couple of weeks, since I upgraded our Symantec AV, our Internet connection has seemed rather slow.

I have just discovered that our Server is constantly sending data to the Internet and using up all our Bandwidth !

Having spoken to our ISP, they are unable to tell me why or what is going on. They say there are several Std Web links, plus one link using port 5517 which they can?t identify.

Does anyone know what might be going on and how to stop it ?

I can supply more info if required

Regards, Dave