A black (Cat5) cable will run from inside your charger to the back of your home broadband internet router/box (the box supplied by your broadband provider, e.g. a BT HomeHub)
The cable is plugged in to your home broadband Internet router/box with a plug that looks like this:
Check that this plug is plugged in to your Internet router/box properly: to remove press down on the plastic spring-latch – reinsert firmly until you hear a “click”.
Your router will probably have multiple sockets for this type of plug. Choose any one, except ones that may be marked with a red square or coloured red.
See Checking Wired Connection for more help