By Joe Callison
27 May, 2016
A modem converts the signal from your internet service provider, whether it comes from telephone, cable TV, or fiber services, to an Ethernet signal that provides the internet service to you computer or other internet connected devices. It could be called a dial-up modem, DSL modem, cable modem, or fiber modem depending on the type of internet service you have. At a minimum, the modem will have an AC power adapter, an Ethernet output port that provides your internet signal, and an input port and/or cable from one of the following:
a) Telephone jack for plain old telephone dial-up service (pretty much obsolete now)
b) DSL splitter if from digital subscriber line telephone service
c) Coax cable if from analog cable TV service
d) Fiber optic or coax cable if from digital TV or fiber internet service
The modem may provide an output port for telephone service through the internet, in which case there is usually battery backup power for the modem to maintain emergency 911 telephone service during brief power outages. This is important to know, because when a modem is not working properly and needs to be reset, it cannot simply be powered down and back on again to perform the reset if it has a battery backup. It may have a physical reset button instead, but be aware that modems (and routers) may also have a small hole that says reset that is only for resetting to the factory default settings and should never be used to trouble shoot a modem or router that is not working properly unless you know the administrator password and how to restore all of the settings. Modems are usually leased through your internet service provider and configured by them, though you have the right to purchase and configure your own from a list of models they have tested and approved.
The modem may also have a router built in, which would have multiple Ethernet output ports (typically 4) and may or may not have wireless (wi-fi) included with either an internal hidden antenna or one or more external ones. If wireless is included, there may be a default wi-fi password printed on a label somewhere on the modem/router or else the password must be configured in the router settings.
The router “routes” the internet signal to and from each of the Ethernet ports and the wireless internet users, if included. The router also includes a firewall to help protect against unauthorized access to your connected computer devices through the internet. The router may have other advanced features not typically needed for most users. If the router is a separate device from the modem, then the modem internet output port would be connected by an Ethernet cable to the router wide area network (WAN) port. The router local area network (LAN) ports would be connected by Ethernet cables to computers and other internet connected devices, which could include Ethernet enabled printers, scanners and voice over internet protocol (VoIP) telephone devices such as Magic Jack, Vonage, Ooma, etc. Settings for configuration of the router are typically done either through a web browser using an internet address designated by the manufacturer for the router such as 192.168.1.1 for Linksys brand routers or sometimes by software provided on a CD that simplifies communication with the router and its settings. If the router is a separate device from the modem, it could be leased and configured through you internet service provider or you may have the option or have to purchase and configure your own. If the modem or router does not have wireless capability, you can easily add it by purchasing a wireless access point (WAP) that would connect to one of the available router Ethernet ports.
If you need more than the 4 Ethernet ports typically provided in routers, then one of the ports can be wired by an Ethernet cable to a network switch which can have 4 to 48 Ethernet ports. The network switch ensures that only one of the switch ports is communicating with the router at a time to avoid data collisions between ports, which would occur in a simpler (and cheaper) Ethernet hub if it were used and could slow down the communication with the internet.
When you are unable to get an internet connection, it is often advised to restart each of the network devices in the order that they are connected, beginning with the modem, then the router, then the switch or wireless access point if provided, and lastly the computer or other connected device that is not communicating with the internet. Network devices (except a modem with battery backup) can be restarted by unplugging their AC power adapter to power them off, waiting 5 or 10 seconds, and then plugging the adapter back in to power them back on. Wait another 5 or 10 seconds before restarting the next network device in the sequence. Lastly the computer can be restarted using the normal shutdown or restart method through the operating system software (accessed from the Start button for Windows computers). This usually clears up the problem, but if not, then you can use the individual network device indicating lights to try and diagnose the problem as explained in the user manual for the device. The user manual is often provided as a PDF file on a CD or can be downloaded from the manufacturer’s web site by looking for support downloads for your particular device model number.