|You cannot connect a mobile internet dongle to a router since router's don't have a USB input port.|
There are two types of mobile internet dongles:
The "standard" and most popular type plugs in to your laptop and can only be used on the laptop it's plugged in to - it cannot be shared across several computers at the same time.
The "sharing" type is a cross between a USB dongle and a wireless router, and network 3 refers to these as "mi-fi" dongles. That's the type you need if you want to use it on more than one computer. Some mobile networks cannot supply you with one of these, in which case you will have to try a different network provider.