Why isn't my cable modem SBV5220 connecting to the internet on 2 computers using an Ethernet Switch?

Are you using a router?

A cable modem such as the SBV5220 without routing functions only outputs one IP address via DHCP.

Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks. Computers that are connected to IP networks must be configured before they can communicate with other computers on the network. DHCP allows a computer to be configured automatically, eliminating the need for intervention by a network administrator. It also provides a central database for keeping track of computers that have been connected to the network. This prevents two computers from accidentally being configured with the same IP address. http://en.wikipedia.org/wiki/Dynamic_Host_Configur...

If you are not using a router, you can only have one computer connected to the Internet at a time.

You can use a switch to add more ports to a local LAN or to a router, however it can not manage the WAN connections from a cable modem without a router.

Here is how it works:

When you are connected to the Internet, you actually have two different IP addresses, a private LAN IP and a public WAN IP.

A router connects two separate networks and manage the traffic between them.

In most home network applications the router connects your local group of computers and devices known as the LAN with the Internet, commonly called the WAN or Wide Area Network.

The router usually assigns unique Local IP addresses to all of the devices connected to it via a service known as DHCP. The addresses assigned by your router are private addresses http://en.wikipedia.org/wiki/Private_network and are not routable across the Internet.

Your cable or DSL modem will get a Public WAN IP address from your ISP's DHCP service. These public IP addresses are leased in blocks by your ISP and are Internet routeble.

A wireless router enables you to provide wireless (WiFi) Internet access to all of your WiFi enabled devices such as laptops, game consoles, cell phones and tablets, etc.

Wireless routers are fairly inexpensive. http://www.amazon.com/s/?_encoding=UTF8&linkCode=u...

As far as the brand goes, the brand is not as important as the model. Some manufacturers release a good model but the next is crap. I would look at the Amazon reviews of models that interest you. Even if you don't buy from Amazon the reviews will tell you a lot about which models to avoid. Look for at least 15 or more reviews with a 4 star or better rating. Read a few and see if they sound like the particular model will work for your application.

Good Luck...

If your modem has two connections then sure. Or else there are a quantity of choices. The high-quality is to get a router (standard10/100Mbs will do for internet. For futureproof then a 1Gb maybe useful but not likely). This can be a box that "routes the knowledge that it recieves to the place it is meant to head. You may join the modem and PCs to it. Otherwise which you can conect the Modem to at least one computer after which that pc to the nect. For this you possibly can need either two ethernet ports on the primary laptop (that you would be able to set up a brand new card yourself and it is a good introduction to enjoying inside your laptop as it's so easy. Or you can get a USB ethernet port). Otherwise you would use firewire (when you don't have it it's more often than not no longer worth getting. The opposite option is a variation on the router alternative which is to get a wireless router. This maybe pricey as you may need to make sure you could have the router and as a minimum one wi-fi reciever for your pc (the other pc might be linked by way of a cable). This could be beneficial if the desktops/one pc are not near the modem. Nonetheless it might even be probably the most highly-priced. Any questions then please believe free to email me

Unless your cable modem includes a built-in router or you have a plan from your ISP that gives you more than one public IP address, your ISP is only going to give you 1 public IP address, so only 1 device at a time would connect to the internet through a network switch.

What you need is a broadband router (or wireless broadband router if you have any WiFi devices). I would allow multiple devices to connect to its LAN side and would give them IP addresses in a private IP range. When accessing the internet it would masquerade the private IP addresses as your single public (WAN) IP. It keeps track of that using ports so if a reply comes back to a specific port it knows which private LAN IP to send it to.

Note that when you connect a different device (or the router) to your cable modem, you will likely need to either reset it if it has a resent button, or power it down completely for a minute. Then power up the modem, power up the router, then boot your computer or whatever.