Connectivity issues are among the most common problems that are brought to the doorstep of the systems department of a company. This can be caused by a number of things, including configuration changes or the malfunction of connectivity devices, such as in the case of a switch, router or hub. The first thing to do, of course, is to check your physical connections. If something is disconnected, you'll need to reconnect and test it in order to make sure that the problem is resolved. If all physical connections look to be in place, check that the port on the hub to which the cabling is connected is on and working properly. There should be a green light on at the port site which indicates that the port is live and ready to connect. Similar testing can be done with switches and routers. If these look to be stable, then check the configuration of the equipment that's experiencing the problem. It could well be that it simply needs to be reconfigured to accommodate the type of equipment that's been attached to make the network connection.